This is especially dumb when you've spent the last four years pointing out that Bernie did real damage to Hillary by refusing to bow out once he was defeated and insisting he could still be installed at the convention. Now you're going to do the same thing out of spite? Fuck off. I get it, you don't like him, and it's frustrating to have to accept defeat to someone who wouldn't four years ago, but at some point you just need to accept it and start moving toward the unity you claim to value.
Nah, Hillary entered the convention with a clear majority of delegates (and votes, though that doesn't matter). The situation these people are trying to exploit is that if Bernie enters the convention with, say, 45%, with the rest split among variously smaller candidates, say no one getting more than 10%, in theory you could rally 51% of those other people's delegates to one other candidate and still win. It's there so that if you had a situation with like ten candidates, and no one was cracking even 30%, the guy with 29% can't claim victory over the guy with 28%, if the third-place candidate with 25% is actually way closer to the 2nd place candidate politically. But these people clearly want to use it way more cynically than that to scrape out an ugly win against someone with a clear plurality.