"Unified his party". To be clear, almost every general election poll has Clinton getting at least a slightly larger share of Democrats than Trump gets of Republicans. But Trump is also competitive with, if not winning, Independents, which is why he's competitive overall. Of course, it's still really early.
I think independents are swayed by the fact that they see one side speaking with a united voice, and the other side speaking with a divided voice (half of which the content of what they're saying validates the other side, particularly in matchups involving Clinton). In any conflict, this will make the united side seem more credible. It is true that there are still some Republican holdouts like Romney, but the party as a whole is far more united than before, and this has coincided with the Trump surge in the polls. Nothing much else has changed.
To be clear, I'm probably one of the only Clinton supporters who's not angry at Sanders even if he is hurting Clinton in the GE polls. He's entitled to do as he likes, and he doesn't owe Clinton anything.
No he doesn't owe Hillary anything....it's bigger than that. If he wants to see the Democrats retain the Presidency then he needs to tone down his game, IMO. Stop throwing Hillary in such a negative light, and start getting his minions to understand how he and Hillary are more alike on the issues than different. We
get Bernie's message -- the only one he apparently has which he has repeated to infinity. Now it's time for compromise and unity.