He can be charged for private acts, but as long as he used official communication to discuss it with others that can't be used as evidence. Then the stacked courts get to decide what is official and private, so private is effectively immune as well.
Don't worry, they effectively ruled it's okay as a hobby as well by gutting the Chevron defense last week to kneecap the EPA and every major federal agency.
Would it be illegal for Biden to invalidate every ruling this Court has made, including the Presidential immunity one? Or would that lead to a paradox?