Top AND Bottom IRL

I recently saw a post on Facebook about a guy saying he wants to be friends with the people in a Fujoshi/Fudanshi community group (Implying he's not straight) and he posted pics of his self. One gay guy(I describe him as transverstite) commented if he was a top or not.

Realistically speaking, do you think it's rude to assume someone that way especially IRL situations?

As for me, it kinda annoyed the heck out of me since he's asking whether he tops or not which is honestly a kind of fetishization for me(⊙…⊙ )