@abolisyonista does this person already write/have videos about their transphobia? And are they some kind of socialist or just a transphobe? I am just trying to think of more arguments you could use.
There's also the issue that live debates are just generally bad anyway, it's a competitive format that's not actually about challenging anyone's ideas and people on either side will rarely care who actually won, this is why the far right loves them so much.
Written debates can be good in some contexts, but just not with bigots.