Yeah, nope, checks out. If eating pussy estrogenises the male body,... nope, we can't have that. The logical solution is to instead suck as much dick as possible to testosteronise the body as much as possible in order to strengthen your hetero biochemistry.
In high school, I had a bumper sticker that read, “Lesbian trapped in a man’s body.” If eating pussy makes me gay, then I’m the gayest mf’er this side of the Mississippi.
You need to understand that this is not about sexuality, but about patriarchy. For them sex is about power over women, not about pleasing them. Cunnilingus focuses on female pleasure, which is a problem for this world view. Men unwilling to take part in the oppression of women are seen as "unmanly". This is expressed through the accusation of being "gay".
Funny thing is, I’ll bet it’s the exact opposite for cis men. I’m willing to bet that if somebody actually did some blood tests, you’d see a surge of testosterone during and after the act compared to prior arousal. One that likely far outstrips the relevance of any dubious exposure to estrogen. I think we should perform this experiment. Maybe even see if there are differences between men and make some correlations.