Honestly Sofie's explanation of gender identity doesn't make sense to me and I've never heard anyone else in the LGBTQ community talk about it like that.
I don't think just being uncomfortable/unfamiliar with the word 'woman' means you can occupy a space for people who truly sit outside gender norms and/or transition, especially when in all other respects you are binary. I don't particularly like being called a woman but I don't think that has to mean anything - for me the word has a lot of connotations of traditional femininity that I (rightly or wrongly) associate with older women and mothers so can't relate to... But so what? I also like being thought of as 'a person/my name' more than my gender... But who doesn't want to be seen as an individual? If I decided that my discomfort with 'woman' meant I was non-binary (which maybe it does? I don't think so though) then I can also label myself as 'queer' since I'm no longer a cis straight person, and that's another community I can fit myself into without really understanding it.
In the grand scheme of things it doesn't really matter, or it wouldn't, if there weren't trans people struggling so hard for recognition and getting their voices heard. But now anyone like Sofie who is non-binary in some small way can occupy those spaces and speak on trans issues which she doesn't really understand - not wanting to fit into 'man' or 'woman' is one thing, but she presents femme, doesn't have gender dysmorphia and still uses she pronouns. And she will get booked as a 'trans' individual to tick diversity boxes instead of someone else because she is white and cis-presenting. It doesn't seem right.