He has to know he cannot win the nomination. In fact his actions prove he will get zero new superdelegates.
He has defined the race between Clinton and Trump as being a lesser of two evils.
His statements about Debbie Wasserman Schultz are chilling. He does not want her to continue being DNC Chair but also wants to primary her out. Even in 2010 elected republican did not publicly do this to fellow elected republican they let voters and PACs do this. Its one thing not wanting her to be Chair but actively primarying her out of office goes way too far.
All he is going to achieve is the superdelegates massing over to Clinton. Along with democrats losing a five term Congresswoman in a leadership position to be replaced with a backbencher.
By calling Clinton evil well there goes most likely a section of his voters to stay home in November.. if he by some miracle he wins the nomination because of his statements this weekend he may find Clinton voters staying home.
It also proves like Trump if you cross him he will try to destroy you.
This so reminds of 1980 but far more destructive, even Ted Kennedy did not come close to going down this path. Yet we know what the results were. I suspect an even higher percentage of Sanders voters not voting for Clinton as compared to Kennedy voters not supporting Carter. Calling a person lesser of two evils will stick, it stuck when Nader sid there was no difference between Gore and Bush.