Honestly, cynicism is the dumb man's idea of what it means to be smart. Punditbrain shit. Sometimes the public explanation *is* the actual explanation.
I don't think you have some anti-liberal bias - as far as I know this is the first time we've spoken, lol. But it reads like you, like a lot of people, sorta picked up the idea that the least generous, most cynical interpretation is the savviest and most accurate, and it's just not. The Warren camp didn't weigh in until after Bernie already made a definitive "this didn't happen" statement, which, judging by how angry Warren was after the debate, they seemed to take personally. So the campaign issues a statement saying "no, it did happen, but let's move on." That's not really a good way to put Sanders on the defensive considering it didn't come until after he had already set out to defend himself.