Unusual community, I think, fits the bill.
So, mild powerlevel here, but I'm a 40k player. For those who don't know, Warhammer 40,000 is set in a grimdark dystopian sci fi far future. Humanity is beset from all sides and war is the only constant. The SJW in question was a newcomer at my usual game shop, since the owner took a minute or two to greet him and he doesn't usually do that for regulars. I wave, being polite, and turn back to the group I was setting up a game with. SJW sits near us to watch, since he expressed interest in maybe learning the rules and playing a game. My opponent says yes, and I'm not too bothered so what the hell, right?
Now, by this point we had finished up deployment and our armies were mostly deployed. His army was Imperial Guard, Night Lords for me. What I can only imagine caught SJW's eye is the smattering of third party minis scattered in my opponent's force. To be specific, he had auxiliary forces and second line units made from female minis. They were rather well done and nicely painted to fit in with the rest of his force, but still a relative minority in his force since his front line units were Cadian minis and there were quite a few on the board. We start playing, and SJW occasionally asks clarification on rules and whatnot, all the new player stuff. Second turn rolls around, and it happens. I deep strike a unit of close combat specialists into his second line and send them on a merry hunt for his lovely female minis with lightning claws and chain weapons.
Cue SJW: Why are you attacking them?
Me: I'm trying to win and his second line has heavy weapons.
SJW: No, why are you attacking the female characters?
Me: ... I just told you.
My opponent: The ladies are soldiers too in this regiment. What's wrong with that?
SJW started a mini rant at this point about how my strategy was sexist. Sexist, because I wanted to win. Sexist, because the mortars crewed by the womenfolk were shredding my cultists and I wanted them silenced. My opponent stops what he was doing and looks sideways at SJW, with the shop owner watching us since SJW is doing nothing to keep their voice down. At this point, I ask SJW what they would do in my situation since I've lost my patience. I get told that I shouldn't move infantry up the middle where mortars can shoot them. What about when I'm near the guns, I ask. Take the crews prisoner, I get back. I say that there isn't a rule for that, and it would be stupid to have. The resulting mini rant had some version of, "killing women at all is sexist and therefore bad" somewhere in it. Now the shop owner comes up and asks SJW to leave because the ranting has distracted three other RPG groups from their games. SJW huffs and what I can only describe as half stomps his way out the door.