I'm not saying that you're necessarily wrong, but is it really necessary to police language to this extent? I get why "cis" is offensive. I think it's a word that's primarily used as a tool to silence women. However, those of us coming from libfem backgrounds have been pretty well conditioned to use that kind of language. Deprogramming that is a process, and being yelled at about it in a place that is supposed to be supportive isn't particularly helpful.