OK, I agree about Cuomo. He's a sleazy guy. But his cancellation of NY primaries was the opening shot. My point is valid. They'll dump Biden under the bus in a New York heartbeat so the Dems can win the presidency. They're not going to let sleepy Joe ruin it for them. Watch Trump come out with a twitter saying that the Dems are now trying to take it away from Biden like they did Sanders. This is going to become a free-for-all. American politics is going to become really interesting this year.
You seem to be assuming the Dems don't think Biden will win. The whole reason he won the primaries was the assumption that he CAN win, and I think it's a good assumption. He's leading in Florida, and Trump can't win without Florida. He's leading in Pennsylvania (where he was born) and in Michigan, and if he wins those two, even without Florida, he wins, as long as he holds Minnesota, where he's leading by 10 points. He's almost certain to win the actual vote count, because he'll win the Blue states by huge margins, while, if Trump wins, it'll be purely on the basis of the Electoral College, and he'll win the critical states there by small margins. So, even if he wins, which I think is unlikely but possible, Trump will again be an illegitimate President, the choice of a minority of Americans.