> [I am opposed to the situation that] any claim to be male, female, non-binary or whatever must be accepted at face value
That is exactly what GP was implying - that their self-image does _not_ have to be accepted.
Would you be for puberty blockers so that puberty can be delayed until 18 and automatic sex transformations be paused until the person can make a decision which way they want to go?
An open conversation and a working plan for what they want to do later in life is a good thing. I'm not opposed to hormone therapy as an interim measure. But I'm opposed to catering to teenage whims that aren't thought through very well, or discussed well, or which are driven by a desire to be part of a popular group, because I've seen the results. Confusion and self-hate and self-destruction can happen as a result of not being able to express yourself, but they can also happen as a result of too much unrestrained emancipation for a teenager, who doesn't understand the consequences. I'm not even speaking about trans issues here, just about teenage decisions in general. They're not fully rational people. I wasn't, either.