Making broad generalizations about a group of people isn't a good thing to do. The way some people speak about "the cishets" is not in any way better than how homophobes broadly generalize LGBT people, I think it's understandable that such only divides people more so than it needs to. 90% of the time what they really mean to say is homophobes, but put it as a broad generalization towards such a large group of people without hesitation. There's plenty of disdain towards them as well, I've seen it in communities, as a bisexual attacks on heterosexual relationships "hurt" just as much as attacks on homosexual ones, so do better.