I said it would not surprise me it it has happened. I did not say it has happened or that I know of a scenario where it has happened. Just that with the vast time and population different ideas cultures and groups that have existed the possibility exists.
I heard that one of those school shootings was actually about that. I'm pretty sure it's one where a teacher was firing or something. The thing about it though was she was feeling bullied about it, so it wasn't just random straight hate, but firing back.
Well, plenty of people got killed for adultery, having sex out of wedlock, etc. It's not like people wouldn't apply hateful and unnecessary rules to pretty much everything...