Nullification is not needed in this case. It is a classic self case where he was defending the well being of another, i.e. his son.
It is pretty clear another was being harmed or threatened with harm. So he acted to defend that person.
He was acting in the defense of his son, but these were doctors he’s threatening with the gun.
Of course, glad to see he’s out of jail. I would NOT have convicted the man of anything. He’s been through enough.
Seems like a TV movie.