This is one issue where I am 100% on the “conservative” side, and indeed the more I read about it the more entrenched I become in that position.
We know, and it's sad to see. You're even more reactionary on this than several (possibly even most?) blue avatars around here.
I don't know what interactions you've had IRL with trans people, if any, but I hope at some point you'll get to do so and spend most of the conversation just being quiet and listening.
The thing is that the student in question probably wasn't trans. That's the real issue here.
Based on what? What standard of proof do you need to accept that someone is genuinely trans, if you don’t believe them when they socially transition, and don’t think they should be allowed to medically transition?