That’s not exactly the reason, no, and I certainly wasn’t trying to suggest that he should survive solely because he’s gay. However, if the only gay character (aside from one who only exists on the other side of a telephone, and whose orientation, to my knowledge, was never revealed, and a couple of others who I didn’t even notice) does die, then it can feel as though the universe is out to get us (and it does happen a lot). I get the feeling that it’s probably the other way around for women; quite often fiction would spare women when they wouldn’t spare men (or make the death far more special, if they do die), and I would agree that this is just as bad. Please don’t think I’m trying to denigrate anyone; I know that as a white, cis male, I’m three-quarters of the way to being completely privileged, and I will always try to look at things from others’ points-of-view.
As a more personal (in this case) reason is that he’s explicitly described as being a gay teen’s crush (and straight females, too, but that’s not reciprocated), and given that the teen MC has one of the most horrific prologues of them all (especially compared to the student, or anyone who goes on the date, and some others), I just felt it would be a nice bright patch in an otherwise-grim, depressing existence (and yes, I get that a zombie apocalypse is going to be grim). (Also, he has the same name as me, and while that was the reason I noticed him in my first playthrough, it doesn’t actually have any bearing on my feelings in this case. )