Datun, I can't speak for clare, but I've just had this question answered by a friend who is a trans man. He says that he has suffered from severe body dysphoria all his life. Since he began socially presenting as masculine, he finds that the dysphoria has eased, and he has achieved something approaching an equilibrium. So for him, the dysphoria is very much about how he is perceived. He says that, if he had a consistent social circle, this might have been enough. However, his work involves lots of travelling within the UK and meeting new people, and despite his best efforts at introducing himself beforehand, he finds he is constantly 'misgendered' - read as female - and this throws his equilibrium off again. So now he wants to use T to enable him to grow facial hair and deepen his voice, to make this less likely to happen. (His body shape means that top surgery isn't necessary, as he also seriously restricts his food intake to keep a flat chest area.)
So in his case it isn't a question of hostile/negative reactions per se, although those things definitely do happen to him. But it's also a question of reactions that aren't deliberately hostile. He experiences the word 'she' as deeply traumatic.
This is exactly the type of person who I worry will be actively harmed by the current transactivist dogma. He is a gentle soul who just wants to live his life. Presentation and perception are all-important to him. I can't imagine him shouting about his 'male cunt'. I can fully understand why, in our gendered society, he suffers from this hideous dysphoria, as part of his wider MH issues. For example, he suffered terrible abuse pre-transition, when he was a masc-presenting lesbian. I wish him all the best in finding peace with himself, but the root of his situation is not that he is really a man who is inappropriately being perceived as a woman. It's the fact that he hates his natural body and wants people to think he has a different type of body, and is terribly distressed when his efforts are not successful.
It also to my mind illustrates the need for trans-specific spaces. If the TAs get their way, and any self-declared woman, regardless of presentation (and presentation is all-important to my friend) can enter spaces that were set aside for biological woman to counteract biology-based oppression - what good will that do him? The fundamental issue is male violence, and he will be no safer from that than ever he was. Nor will any woman, trans or biological, because all spaces will be open to all men.