This is why trans people won't be accepted in the ways they wish -- they alienate even those who are open-minded and willing allies. They assume negative intent from anyone who isn't trans themselves.

"I've never been with a trans boy before. My brain is open-minded, but my penis might not be."

I don't see anything wrong with that statement. Good for that guy for being honest. It shows he's open to being with a trans guy (so he's not saying 'no' and is clearly attracted to some), but also being upfront about the fact that he may not be into it once naked and actively engaging in sex. Why is that such a negative thing? Were it me, I'd appreciate the heads up. It's one thing to not be into a specific person (ie it's personal) and quite another to not be into a specific kind of genitalia (ie it's not personal).

I'm not surprised they trotted out the old "what if a guy had his dick shot off" thing too, even though it's not the 'gotcha' they think it is. Also, maybe it's just me but I think it's pretty darn offensive to compare males who've suffered genital injuries to females (regardless of whether they 'feel like men' or not).