The counterpoint is both obvious and obviously correct. Assume we accept that the President has immunity for whatever constitutes official conduct (which this decision does not get into). Presidents have fixed terms, so unless ex-presidents have immunity, they can be prosecuted for anything they do in office, including their official duties. That would make it difficult for the president to take action while in office.
Can we prosecute Obama for ordering drone strikes on U.S. citizens? Can we prosecute Bush for the Iraq war? Can we prosecute Biden in a few months for deaths caused by his border policies?
Also, this is just how immunity works! Judges have immunity for their judicial conduct in office, and don’t lose it when they retire. When the GOP wins a trifecta next year, can they prosecute retired liberal justices for homicide for abortion rulings?
Can we prosecute Obama for ordering drone strikes on U.S. citizens? Can we prosecute Bush for the Iraq war? Can we prosecute Biden in a few months for deaths caused by his border policies?
Also, this is just how immunity works! Judges have immunity for their judicial conduct in office, and don’t lose it when they retire. When the GOP wins a trifecta next year, can they prosecute retired liberal justices for homicide for abortion rulings?