It seems to me that Biden’s shoulder rubs and hair-smelling, won’t sink him. It’s weird and inappropriate behavior, but not sexual or malicious.
(There’s some doubt out there about the specific Lucy Flores story by the way, even if it seems plausible enough):
Flores: Biden touched me inappropriately while I was on line with other speakers.
Munoz: She’s wrong; they were never alone together.
— Matthew Yglesias (@mattyglesias) March 31, 2019
If Biden routinely crossed the line into honest-to-goodness groping, though, it’s inevitably going to come out and will end his proto-campaign or actual campaign in short order.