“compulsory heterosexuality” is a theoretical term that is used in academic feminism. It is awful that TERFs are trying to co-opt academic language, but theoretical language doesn’t change just like that because a hate group is trying to claim it. Just “heteronormativity” or just “cisheteronormativity” aren’t the same theoretical construct and they can’t be used interchangably, although coercive heteronormativity is an alternative term and we do tag comp het posts with that too (or at least I do, I don’t fully know what the other mods tag) and I try to mention it in those to.
The thing with TERFs is that they are, at their core, transphobes that try to hide their transphobia behind real academic feminism, and if we stopped using all the construct they’re trying to co-opt, we would end up without any words to use at all, and they would sit on a mountain of theoretical concepts, and that would just lend them more power. If we refuse this co-opt and keep using the term, they cannot claim it, but if we give in, it will be theirs.