I mean, he isn't entirely wrong. A bit of a douche, but sexuality isn't purely binary, and it really is about what you're actually attracted to rather than what you can "make do with".

Another way of looking at it is that if you aren't into the person sexually, rather than just human contact as opposed to masturbation, it isn't something that changes your core orientation.

Now, I would still think of that as being into the bisexual section of the slider, but I prefer not to place labels on people when they don't want them. Dude says he's straight, doesn't matter what my personal opinion about where boundaries switch are, he's straight.

Also, it pretty much all feels the same in the dark, mouth and anus anyway. Or so I've been told, never done the whole "dark room" thing myself.