“Jill Stein is a useful idiot for Russia. After parroting Kremlin talking points and being propped up by bad actors in 2016 she’s at it again,” DNC spokesman Matt Corridoni said in a statement to The Bulwark. “Jill Stein won’t become president, but her spoiler candidacy—that both the GOP and Putin have previously shown interest in—can help decide who wins. A vote for Stein is a vote for Trump.”
Not just Trump will be worse as some sort of abstract moral statement. Their statement is that Uncommitted voters should actively vote against Donald Trump no matter how inadequate Harris’s statements and commitments have been.