I can't really say I am offended by the comic, but I don't like it, that's for sure.
In regards to the pre T thing, he mentions being interested in trans men after they have only been on T a few months. At that point there is very rarely that much physical appearance differences, and in fact that pre-T character looks the same in both panels both pre and post T, which is fairly accurate. The main things they would have at that point would be possibly some down stairs growth, if they are incredibly lucky the voice might be starting to crack, they may have acne. But no significant changes such as noticeably facial hair usually after only a few months on T. The cis gay male character is also shown as just completely ignoring the pre T guy entirely even as a friend prospect, then all of a sudden is really interested after just a few months on T.
The comic just seems to be one gay guy being as obsessed about his orientation as he perceives others to be. He seems more concerned about still being considered a "gold star gay", which IMO is just really immature and petty labeling, than about the trans men themselves being treated as men.