Well you are right. But even if he was president he still couldn't.

If Hunter is pardoned he can be put on the stand and forced to correctly answer any questions related to the crime. He would not have fifth amendment privileges. This puts all of Biden's business partners in jeopardy as well as himself. It also puts him in jeopardy of perjury as well as contempt of court and contempt of Congress.

Their safest route is to rig a trial. If they fail they can still fall back on a narrow pardon, but then they can spin it by saying the court got it wrong. If they pardon anything before a trial it's a confession of guilt in that they are saying that they don't think they will win.