Maybe you should just accept that this candidate has lost the trans vote and move on instead of demanding trans people and their allies support their demise. It's not trans people's fault this candidate is anti-trans. Don't go after trans folks just because their voting decisions aren't "perfect". When a candidate says he is anti-trans, it seems absurd to castigate trans allies for believing him.
Sure, it's too late to get a different Dem candidate, but that just makes it more important that the Dem candidate doesn't make dumbass decisions to needlessly throw away voters for zero benefit. It seems like a bad use of your time to go after the many people in the voter base this candidate is alienating. It would be more efficient to rebuke this single candidate and demand he apologize.