I'll repeat myself because my argument seems to not be clear enough. I'm not saying that TERF can't be used as an insult, but what i am saying is questioning the term itself is a pretty good signalling of someone who does seem to question trans womans rights to be included in feminism. Trans peoples humanity isn't up for debate when you ask me. When someone does so they are the ones who suppress a debate, not the people who call them out for being a TERF. I agree that the experiences of womanhood of trans womans are different to those from woman who have not transitioned. But that is no reason to exclude trans woman from feminism, if you do so your feminism isn't intersectional.
I'm not saying those 1,000 Corbyn supporters are actual anti-Semitic racists because they find it offensive to be called one. But when all those 1,000 Corbyn supporters would reply with how anti-semitic is a problematic term, you would probably scratch your head wouldn't you?