The takeaway is obviously different though: for me the “and therefore.. ” is that “and therefore, all trans identifying people should use the correct facilities for their sex.”
Indeed. After all, that's the only way to treat all trans people the same way, isn't it? For example, non-binary people don't identify as either gender, so where should they go? They can't use either male or female facilities, since they don't identify as such, so they have nowhere to go! Same with agender people, who identify as having no gender, and thus cannot go anywhere either. Arguing that trans people should use the facilities which correspond to their gender is discriminating against some trans people, which this person says shouldn't happen:
"However, the answer to that — as trans people and allies — cannot be to start throwing each other under the bus. If one portion of the community gets to keep their rights but everyone else lost them, that’s a loss for all of my trans siblings."
Well, mate, that's exactly what you're doing by arguing that people should be free to use the facilities corresponding to their gender!
The only way to treat all trans people the same, is to have them use the facilities corresponding to their sex, because every trans person has an immutable sex, which was observed (not assigned) at birth.