If i'm reading this correctly.....
If the ball was in the forest and the forest is out of bounds, then he was right to play the provisional. And he is shooting 4 from the provisional.
You can't play a ball that is OB, even if it by a half inch and you have a perfect lie....if the forest is not marked OB, then he would have to play it, decalre unplayable or go back..right?
You can't only play by some of the rules (i.e. let him drop and play it 4) because that is no different than dropping and playing it as shot 3...neither way is correct.