I doubt being grumpy about Sanders is going to shift folk to be right-wing. A lot of them probably HAVE become tankies but… the Sanders campaign was already very heavily buoyed by tankies online. Because it would have been shooting fish in a barrel for the candidate most known for “fun nicknames” to be up against a guy who used to be a meme about how c-span was boring and actively refused to even say “While I think the socioeconomic model had a lot of benefits, I oppose the fascist communist regimes of olde”.
But also? I know a few of the dumbest “Bernie or bust” morons you will ever see who focused that anger toward working with the Democrats to get considerably less shitty downballot candidates. And that is what the lesson should have been.