Thirty has been trying to sabotage Democrats for years now despite the repeated failure of all his chosen candidates and (alleged) causes.
He cares so much about progressive causes that he didn't even "vote against" a racist president and Republicans taking the Supreme Court.
This is why he conveniently ignores when moderates win midterms or general elections by historic margins -- he'd rather Democrats lose.
Even when moderates promote and pass progressive legislation he ignores it -- that's proof that he doesn't care about real progress.