Yes, and detransitioners happen and should be (and are as far as I've experienced) supported. But their argument a bit like if I said that all elective surgery should be illegal because I regret mine. For every story like this you can find a thousand who are waiting years to get any amount of treatment. The UK is well known for having some of the most stringent policies and heavy usage of gatekeeping before anyone gets treatment - FAR more than in the US.