I don't think your parents not intervening necessarily reflects badly upon them; I can only imagine being parents of a sapphic nature comes with its share of difficulties, much as I imagine being the child of such parents would make you a target to teachers and schoolmates alike. It's quite understandable that they should not want to add the burden of being the "confrontational" parents, both to you and to themselves.

Still, it is odd to denounce a parent standing up for their child as "threatening". I agree that the other person's initial comment came off as possibly being the rantings of a deranged helicopter parent. However, if their second comment, to which you replied, is to be believed, I find their objections to be just and right.

I have many friends who teach as their trade; I've no doubt that the plight of educators at the hand of undignant parents is more oft than not of a ridiculous nature; parents being very protective of their offspring. Yet we must not perceive this tendency as eternally true, as yet some are amongst the educators who should abuse the trust of old between master and pupil.

(Sorry I'm stoned and have been reading a lot of Tolkien recently; so I started replying, a bit subconsciously, in his style. I put too much into it to delete it, so please forgive my indulgent follies)