... but hurting him ... and not blowing up the party completely.

Biden saying insane shit the "Left-of-Center Billionaries" can handle as "Because he doesn't mean it completely, and our little carve outs will be safe, so eff the peons."

Bernie, however, can rile the True Left. He still would be a long shot. But he'd drag the party itself off the edge completely. The middle would revolt. Several of the core factions that aren't "Pure Communists" but actually think they're "just victims" would break ...(They're currently in a Cliffhanger situation, and they know it.)