A real talmid chachom needs to be cruel and insensitive to his family?

A possible explanation of the parameters of insensitivy is presented in later post Alter Rebbe admonished his son for insensitivity

Eiruvin(21b-22a): His locks are curled (Shir HaShirm 5:11). Mar Ukva says that teaches us that we are to make many interpretations on every point of the letters of the Torah. black as a raven – With whom do you find this ability? It is with he who gets up early (shachar – shacharis – Rashi) and remains late (aruv – aravis – Rashi) to study Torah. Rabbah said you only find this ability in a person who blackens his face like a raven (from hunger and deprivation). Rava said this ability is only found in someone who makes himself cruel in relation to his children and wife – as a raven. [And therefore G‑d provides insects which go into their mouths - Rashi] Someone such as Rav Adda bar Masnah who once when leaving to study Torah in the beis medrash was stopped by his wife. She asked him how she would be able to feed his children? He responded by saying, Are there no more edible herbs that can be found for free in the marsh?
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Kli Yakar (Devarim 33:9):Who said to his father and to his mother, I have not seen him; nor did he acknowledge his brothers, nor knew his own children; for they have observed your word, and kept your covenant. That is because our Sages (Megila 17a) said that whoever is involved in Torah study is exempt from honoring his parents. The proof of this is Yaakov who was not punished for the 14 years that he remained with Shem and Ever and did not fulfill the mitzva of honoring his father and mother. This is what the verse is saying that “He says to his father and mother that he hasn’t seen him” because he is not required to look after them and surely he doesn’t not have to pay attention to what his brother is doing.Furthermore the verse says He doesn’t know his own children.This is stated in Eiruvin (22a). “What is the meaning of the verse (Shir HaShirim 5:11), “black as a crow.” Rava says it is referring to talmid chachim because of the necessity for him to be cruel to his children as a crow in order to be proficient in his studies. An example is Rav Adda who when he was leaving to study in the beis hamedrash his wife asked him where his children would get food. He responded that there were herbs in the marsh that they could eat.” This that it says in this verse that “he doesn’t know his own children” it also means that his children act as if they don’t know their father. That is because they also are studying Torah and thus don’t know him.

Maharal (Tiferes Yisroel #63):  Eiruvin (21b),” (Shir HaShirim 5:11) curled locks black as a crow. Mar Ukva says it teaches that every aspect of Torah should be interpreted to produce many halachic understandings. Rabba says it indicates that Torah mastery depends on deprivation of food which is indicated by the face darkening like a raven. Rava says it means Torah mastery is depends on being cruel to one’s family and wife as a crow.” The underlying concept of expressed in this gemora that the great amount of halachic knowledge which is indicated by curls – they in fact are refined abstract understandings (hasagos hanivdalim) that are separate from this world and are far from the man who is materialistic. That is why the gemora uses the language “with whom do you find these halachos” The first answer is one who devotes his mornings and evenings to understand them. In other words Torah mastery is found in someone who turns his back on the material issues of this world and instead devotes all this time to study these matters. That is because it is impossible that he be a talmid chachom if he is immersed in the material issues of the world. Rabbah provides a higher level in that a real talmid chachom needs to darken himself. That means not only his thoughts are turned from materialism but that he minimizes his physical connection with the materialism of eating and other comforts. In this manner he is fit to acquire these concepts which are separated from a person. The third level described by Rava is to be so separated from this material world that he is cruel to his children. This is a higher level of separation then depriving oneself of material enjoyment such as food. The significance of this is clear that one who is not merciful to his own children has overcome his material nature to a higher degree than one denies himself food. Thus he is more able to acquire these non-physical concepts which are alien to the man immersed in physicality.

Rav Yitzchok Zilberstein (Chashukei Chemed Bava Basra 73b): Question: A father-in-law sees that his son-in-law is a great masmid - however he doesn’t bring any income into the home and his children are going hungry. He is very disturbed by the suffering of his daughter and his grandchildren. He wants to intervene and to request that his son-in-law go to work and provide properly for his family. What can be said to the father-in-law to dissuade him from intervening? Answer: It says in Bava Basra (73b) “Rabbah b. Bar Hana further stated: I saw that frog the size of the Fort of Hagronia. (What is the size of the Fort of Hagronia? — Sixty houses.) There came a snake and swallowed the frog. Then came a raven and swallowed the snake, and perched on a tree. Imagine how strong the tree was. R. Papa b. Samuel said: Had I not been there I would not have believed it.” The Gra explains the significance of the frog according the medrash. Why were the Egyptians afflicted with frogs? Because they prevented the Jews from studying Torah like the frog that didn’t stop day and night. That is the meaning of “that frog” – meaning a great Torah scholar. “The size of Fort of Hagronia which was the size of 60 houses” – alludes to the fact that the scholar reads and learns with his throat (garon) – 60 tractates which he has mastered. “Then a snake came” – that is referring to the yetzer harah which is called snake which stays close to the talmid chachom to prevent him from studying Torah because of the lack of food. Then the crow comes and swallows the snake. This is explained in Eiruvin (22a) regarding the verse “black as a crow” – that one who make himself a cruel as crow regarding his children. That is because the yetzer harah tries to seduce the person to stop learning because of the lack of food. However the one who makes himself as cruel as a crow and continues learning Torah day and night – then G‑d Himself provides them with food. That is the significance of the crow sitting on the tree – that G‑d Himself supports the talmid chachom like in a Yissachar Zevulen relationship. “Thus imagine powerful that tree is” – meaning how great is the power of those who support people who study Torah from the fact that Yaakov and Moshe preceded the Berachos of Zevulen to Yissachar. And a certain talmid chachom related that immediately after the war the Brisker Rav met the Mastrikover Rebbe. Both of them had lost many family members. The Brisk Rav said, Our Sages tell us that the verse, “Man when he dies in the tent” teaches us that Torah is only mastered by someone who is willing to kill himself for it. One can also interpret these words to mean that a man is obligated to kill his emotions in order to learn Torah. 

Orchos Tzadikim (Gate of Cruelty): Up to this point we have been describing how how bad cruelty is. However there are situations that in fact require a person to act cruelly against the wicked... Furthermore our Sages (Eiruvin 22a) say that Torah scholarship is found in a person who is cruel to his family as a crow and it cites as an example the case of Rav Ada bar Masna who was asked by his wife as he was leaving to learning in the beis medrash how his children were to be fed. He responded they can eat the herbs growning in the marsh. It is obvious that a person who shows too much kindness to his child will focus on making money and he will not be so concerned on whether the money is obtained legally or not. That is because love distorts one’s thinking. In addition because of the effort that he has to exert day and night to produce a livelihood and ample supplies he ends up being idle from Torah study. That is because he makes his work the main thing and consequently his priorities become confused. 

Vayikra Rabbah (19:01)  Seeing that the words of the Torah require to be attended to early at dawn and late in the evening, whence will one's livelihood come, even as it is said, ’ Who shall provide for the raven his food,’ when his young ones cry unto God, and wander for lack of food? This implies: If a man does not show himself as cruel towards himself, his children and his household as a raven to its young, he does not succeed in acquiring Torah.