She got away with her monkeyshines on Sanders and Joe is just lame and stupid enough that she can pull this stunt and succeed.
Mark that
I don't think that's quite the strategy. If he gets the nomination, he has it. My take is that Hillary's cabal would love it for the convention to be deadlocked on the first ballot, perhaps with Biden in the lead and the rest of the socialist candidates split and at each others throat. Then on the second ballot, the super delegates get to vote, and a white knight candidate can come riding in on her white horse.
My bet is that this will be a brokered convention. The old backroom cigar shtick (or vaporizers, to be modern).