That came from your response where Contra had to be presuming other cis women in her group could include non-binary people hence the “until proven otherwise” thing.
But responding to your latter concern, yes, binary trans people are constantly berated by using singular they. It happened to Contra and I witnessed it firsthand. I don’t think it’s an unreasonable expectation to view an automatic singular they with distinct disdain since no cis person has ever their identity questioned to the same extent a trans person’s is.