If opposing Kavanaugh means that Heitkamp loses, then welp... I'd rather have that then the Dems being okay with Kavanaugh and allowing him to skate by, considering he's probably a drunken rapist.
Problem being he would be confirmed anyway, so you're basically throwing one or more Senators in the trash can for zero benefit.
And what happens if Dems did just shrug it off and allow a handful of senators to vote to confirm him and (not """"snatch defeat from the jaws of victory"""" like you seem to be so convinced of) Heitkamp is still down 12? Then we basically caved and made people think we're a party okay with rapey judges. Still sounds like zero benefit.
If the Dems have the upper hand on issues like healthcare, the environment (the red tide and algae in Florida is an example), and wage stagnation, then maybe the party base can take one hit for the team in order to sell the larger issues I mentioned to the public.