Sounds like your average jerk to me, whether he's a gamer, a jock, a revhead or whatever else doesn't change that, where do you come off with the gaming correlation there? You already pointed out one other guy who also gamed, and yourself as well, who also games, seemed against such views. You two are gamers too. Would you speak up against that behaviour in a different environment? If so, why not there? If not, why's gaming the one you point out? And how is smoking him in DBFZ for being whatever that other word you wrote means good retaliation? You didn't speak your views up so your views didn't win over the jerk's just because you beat him. What if he was better at the game than you, would that make his views more important, or have them prevail over yours and make you question yourself? Come on.
Universal rule number 1: if someone self-identifies as a "Gamer" run away. As far as you can, instantly without any second thoughts.
Seems like the OP projected the gamer label there. I mean, if some random asks me about myself I won't call myself a gamer just as I wouldn't call myself a golfer if I happened to play golf, there's no single thing that defines me. Maybe when I was a kid I'd say something like that, not much defined me back then. If someone asks me if I'm a gamer however, then I have no choice by to say yes. I'm not gonna go on a rant about jerks and how I'm totally not like them just because I play games, that's all the term means, to play games, it really sucks to have it turn into some negative term about douchebags, racists, whatever. Call them that, that they happen to game as well is completely irrelevant. What am I gonna say if I'm asked about hobbies, that I'm a game-phil or something to distance myself from a simple word? I mean, in my language we don't have one word to say that, to say gamer, I'd have to say I play video games, I see no reason to beat around the bush and use similar phrasing in English as well to avoid the racist/jerk/sexist/misogynist/whatever label people want to associate in 1:1 with that these days. Just as we shouldn't beat around the bush and call all those things gamer. Gamer means to play games, these days tons of people are, whether you wanna call them that or not, whether they avoid the term because of the forced connotations or not.
Since the OP is anecdotal I'll say my gamer friends back in the day weren't like that either, just your average geek. Generally smart, quiet and calm kids who wouldn't hurt a fly or spend their day judging skin colors and sexual orientation, though the odd gay joke did leak in our circle given society at the time, just as I imagine many here must have been around someone who wasn't a total jerk but still at one point in his early life said a joke involving blondes. or something. Life happened and there's distance between most of us though I also have an online group I still hang out with, a handful of people for the past 20 or so years who occasionally play some new coop game together but generally mostly just discuss games rather than play them, and none of them are such jerks either.