If the republicans go along with it, Biden is a hero who legalized pot and freed tons of blacks. If they vote against it, they are the "establishment" and are racists.
It might be shameless, but it is a very savvy move. The dems don't really want this, and they know it will die in the Senate, but now they throw the onus onto the republicans. People will shift their vote over this. Smart.
It's a move Trump should have pulled before the 2020 election whether he intended to do it or not. It might have been enough to push him over the line.