Mark is cool imo. Just like RotJ when it seems Luke might be turning but then nah, he snaps back and yeets Palpatine into the bin. Can understand some being wobbly but man has been out there tweeting and liking stuff openly and showing explicit support for trans peeps with no prompt for awhile now. Can't see him doing a hard pivot personally, but perhaps I'm naive.
What will keep me guarded is that "trans right are human rights" or whatever is a much more wishywashy liberal thing to say than reinforcing that trans people are exactly who we say we are. Even TERFs will throw in the obligatory "human rights, everyone should be ok" stuff while calling for open genocide so at best he's on my whatever list. Just my take but I've been out for nearly 16 years at this point and am unfortunately now never surprised when general nonspecific "human love peace goodwill" support comes from someone who also buys some percentage of essentialist "baSiC biOLoGy" or "some concerns" about sports or whatever else.