Either Athanasius was transphobic, or he was willing to use transphobia to condemn his opponents

From his History of the Arians:

But the inheritors of the opinions and impiety of Eusebius and his fellows, the eunuch Leontius, who ought not to remain in communion even as a layman, because he mutilated himself that he might henceforward be at liberty to sleep with one Eustolium, who is a wife as far as he is concerned, but is called a virgin.

And from his Defense of his Flight:

Leontius for instance being censured for his intimacy with a certain young woman, named Eustolium, and prohibited from living with her, mutilated himself for her sake, in order that he might be able to associate with her freely. He did not however clear himself from suspicion, but rather on this account he was [temporarily] degraded from his rank as Presbyter.

Leontia was bishop of Antioch from 344 to 358. She used her boiname Leontius in the role, and her ownname is unknown, so at best we can call her Leontia. It is unclear whether she castrated herself and married her partner before or after this was forbidden to presbyters and bishops. Note that judging by this translation [in the Schaff version], Athanasius degenders both of them, using male pronouns and her boiname for Leontia, as well as a neuter name for Eustolia.