Biden's groping tendencies were extensively discussed in the early primary days. As was the allegations of Tara Reade, both her initial claims of harassment, and the later claim of sexual assault.
And Ilhan Omar got quite a bit of blowback about that comment. And I don't mean the utterly insincere horseshit on Fox, but from large swathes of the liberal media, including very unflattering comparisons to Jeremy Corbin.
As for Biden, I think it's a crying shame he's the nominee. Whether he sexually assaulted Reade or not, I do not know, but there's enough of a pattern of troubling behavior that it's ludicrous to dismiss her allegations out of hand.
Comparisons to Kavanaugh don't make sense though. It isn't like every alternative to Kavanaugh had significantly worse allegations against them, including a literal recording of them adminting to sexual assault as a matter of course.
You take Trump as the opposition out of the picture, and there's 0 chance Biden would have been the nominee. A large proportion of the Democratic party is doing what a large percentage of the Republican Party did in 2016: holding their nose and voting against the other side.