Prohibition to return to Egypt was only temporary

 Rabbeinu Bachya (Devarim 17:16) “and the Lord has said to you: “you shall not return again on this way.” This commandment was valid only during the period when it was promulgated. It was intended to ensure that Israelites traveling to Egypt would not learn to copy the abominations practiced in that country as the Torah spells out in detail in Leviticus 18,3. This does not mean that there is a permanent prohibition for Jews to reside in Egypt. Had the Torah intended these words as a permanent prohibition it would be inconceivable that so many Torah scholars, pious individuals, made their home in Egypt after the destruction of the Temple. Even if individual Jews had ignored this prohibition and settled in Egypt, the sages would have spoken out against this and we would have records of their protest. The only people who were forbidden to dwell in Egypt were Jews who left the land of Israel to do so.