When all this BS started a few years ago, The left figured they had to at least keep up the appearance of applying an equal standard. If I'm being generous, they may have even naively assumed that the net would, on balance, catch more conservative fish. Turns out that men of all stripes want to have sexual intercourse with young women. Who knew?
They regret, now, letting some of their own get taken out. They're starting to figure out that the current milieu is such that they can selectively abandon "believe all women". Gillibrand is a shrewd shrew and knows this well.
The reason NY Dems are piling on Cuomo more than national ones are is that 1) they genuinely don't like him (he's apparently a grade A turd) and 2) many of them have their eyes on Albany and they smell his garlic/pesto-infused blood in the water.