...sigh.
How about, just, try not to be hateful, whoever you are.
Yes, the people who boost this are almost certainly going passive-aggressive about recent Pride events, and yes, it's pretty damn rare for someone to be beaten or killed for being straight, and yes, there are still entire countries where being gay puts your liberty and life at risk.
But I've spent a week watching straight friends preparing for their parts in local Gay Pride events, and it's quite wonderful.
Whereas the reaction to this (not among my friends, thankfully), isn't. This is the kind of crap that puts people in opposite corners, us and them. This is the thinking that you can't win unless someone loses, and it's less important that people stand together than that the groups you hate feel terrible.
People are going to be stupid for a while. Stupid on the Internet. Ignore them, and they'll stop, probably within a month. Be as outraged and hateful as you imagine them to be, and this will drag on, and a lot of people who might be apathetic or sympathetic are going to get the impression the cause of gay rights is full of people who hate heterosexuals.