I honestly hate that gay men feel that just because a dude wants to put a dildo in their ass they want to be fucked by a man. It just so happens at the majority of toys that a straight man can purchase are phallic shaped. Just because a dude wants something in his butt doesn't mean he wants to be fucked by a guy.
It absolutely plays into the horrible stereotype that any anal activity is a gay activity and it's not. And for that matter if he ever does decide that he wants to have someone penetrate him it's on his terms. And having dudes in his DMs all the time, I'm sure, would absolutely send him away from the idea in a heartbeat.