Look, this is a shitty thing, but what exactly is Biden supposed to do here?
He can't fire SCOTUS. If he issues an executive order to counter this it will get litigated. He can work with Congress to try to get a law written, but since we don't have both houses, that's not likely to happen.
If SCOTUS somehow says Trump is above criminal prosecution while Biden isn't...
Seriously, what do you want Biden to do? Expand the Court? The Senate won't do that.