Homosexuality - a heter?

Taz  (Bereishis 2:24):And therefore a man leaves…… The Holy spirit said this because if you say that Adam said it together with “This time …” .That can’t be since it serves no purpose to finish off his statement in that manner. .In contrast if it were said by the Holy spirit and then it is understood as a warning as Rashi explains. And they become one flesh – the Rambam asks “even animals become one flesh  in their offspring?”And in truth this is not really a problem at all because this verse is stated only to prohibit certain sexual relations such as bestiality as is stated in Sanhedrin 58a),”Rabbi Akiva said and cleave to his wife and not another male or the wife of another man and they shall become one flesh means only those sexual relations that result in one flesh through the offspring which excludes with animals because intercourse with them does not produce offspring. And this is what Rashi meant when he was explain the phrase “one flesh” teaches that intercourse with animals is prohibited But we rely on the gemora that “cleave” excludes homosexual relations  because the recipient gets no pleasure as Rashi notes. But why not learn this from “one flesh”because it cant produce offspring but then why is  the word cleave (davak) needed if everything is learned from “one flesh”? it appears to me that without the word “cleave” I would have explained the prohibition of bestiality as because it is lacking in unity. In other words with an animal there is a lack of constant togetherness and that is the reason that they are not one flesh  being together today but tomorrow the animal is with someone else. The Ramban says something a little bit similar concerning cleaving. Therefore I would have mistakenly thought that homosexual relation would be permitted because exclusive loyalty is possible between two males. Something similar is alluded to in the gemora noting that the Persians don’t write a Kesubah for a homosexual couple. Therefore the Torah states and cleaves to exclude homosexuality since the recipient does not get pleasure. But I might mistakenly think that if the prohibition is because of the lack of pleasue and the animal does get pleasure it  is therefore permitted! Therefore we learn from “one flesh” that it is prohibited. And this appears to me to be correct