Quick question, that is only for my curiosity and doesn't come from any negative judgement, are you a straight male?

If you are then good on ya, I should feel silly for being surprised by this take because everyone is different.

But if you aren't; I would say that as a straight male, the thought of potentially getting my dick sucked by a guy but not knowing it was a guy, gives me the same exact feeling as if I did know. It's not disgust for another person, it's just a voiceless feeling that roughly translates to "definitely no", I'm sure someone else could describe it better, I'm no wordsmith, but that's essentially why we don't want to do that.

That being said, if you don't want to involve involuntary aversions, only some people have and nobody really talks about without being homophobic, because maybe you haven't experienced what I'm talking about. I will say getting your dick sucked by a guy is gay in the most literal sense. Maybe you aren't gay, that's on you to figure out, but you did do a gay thing, no "if"s "and"s or "butt"s about it and there is nothing wrong with that.