Well, there are other things atheists can talk about besides how it pisses them off that other people believe in a god. Just off the top of my head:

No, but that's how she related the encounter.

Atheists having meetings seems counter-intuitive to me.

You're kidding, right? No one's asking them to "solely support feminism," or even to add specifically feminist causes to their mission. They're just asking that, when they're at these events, they not be actively treated in a manner that makes them feel unwelcome and unsafe.

I say "relatively trivial", because all the guy did was invite a girl for coffee after they'd been chatting in bar. When she said "no", he accepted that. I understand it was scary for her, but he didn't know her mental state.