Ironically, it generally does seem to be the trans people who aren't hung up on pronouns and who accept being male who it's easy to call 'she'
It makes sense. I don't think any of us want to be deliberately rude for no reason. Probably most of us used to be OK using preferred pronouns when it was simply a matter of courtesy and not compelled speech designed to disappear women's rights. It feels safe to call Fionne 'she' because we know he doesn't have that agenda.
From Helen Saxby's WPUK talk in Brighton:
The phrase ‘transwomen are women’ is naively understood to be simply a courtesy to a male trans person, a sign of allyship. If you don’t join in, because you stick to the definition of women which is biologically correct, you are nailing your colours to the mast and this is risky. There is a huge amount of abuse directed at women who refuse to do as they are told, and this fact demonstrates that the use of ‘transwomen are women’ is not as benign as it first seems. If you wish to be ‘nice’ to someone, that is your free choice, but if you are punished for NOT being ‘nice’ then it is no free choice at all and it begins to look more like bullying and coercion.
...
‘Transwomen are women’ is political dogma, repeated endlessly and deliberately in order to reinforce the message. Because there is #nodebate it has been made almost impossible to counter. For this reason I now reject, as a political act in my turn, the notion that ‘transwomen are women’. It has nothing to do with ‘hate’ or ‘transphobia’ or ‘bigotry’. If the political arm of the Anti Kitten-Stomping League was trying to infringe on women’s rights, I’d fight them too: it wouldn’t mean that I approved of stomping on kittens. It is purely a political defence of the rights of women and girls, against a political movement which threatens those rights. It is undemocratic to threaten and abuse women who speak out on this.