So to answer your question, he must be brave enough to stand up against the Gaystapo by using his real name. Only then can it be proven these really are the words of a gay man. Otherwise, the argument can be made that they are not the words of a gay man, and there is no way to refute that argument.
I honestly hope these are the words of a gay man, but I am left with uncertainty that they are.
Suppose you did know the name of the author. How, then do you propose to go about proving that he is gay? You cannot tell sexual orientation by someone’s name. Even if you knew the author’s real name, you still need to trust that the author is being genuine about his sexual preference.
I certainly can understand why he’d want to remain anonymous, and I find it difficult to believe that you wouldn’t sympathize with that desire as well.