Biden is following an old political axiom. If your opponent is losing the election all on his own, don't interfere.
There is absolutely no comparison between Biden and HRC other than the fact that both have years of experience in government.
Biden is not being investigated by the FBI. Throughout the entire 2016 campaign, voters knew Clinton was being investigated by the FBI. She was even forced to make a statement on national television at a FBI hearing.
Vladimir Putin wanted Trump to be our next President, and his government hacked into the DNC computers. The result: a daily four-month barrage of information released to the public that was extremely damaging to the Clinton campaign. That is not likely to happen to Biden.
Clinton had enormous baggage to haul around during her campaign. Her nomination was an error by the DNC. Biden is pretty clean, very little baggage except for a habit of making gaffes.
If Biden is not being investigated by the FBI, then what happened to Clinton can't happen to him. Eleven days before the election, the FBI director, James Comey, reopened the investigation into Clinton. Her strong lead in the polls melted away during the following week.
A couple of days before the election, Comey had a "sorry about that," it was all a big mistake, and he closed the investigation again. As we all know, Trump won the election.
So, there are enormous differences between Biden and HRC. Trump won't luck out again.
Besides, after 3 1/2 years of the Trump administration rump is that bad.