Ronnie Nunn didn't say it was a legal elbow...he said it was a legal armbar that just happened to catch Gasol up high. Subsequently, the defender went through the offensive player, thus the foul. He also mentioned that they had to discuss the play with in the League Offices for a bit before deciding what to grade the call.
I'll say in real time, I would have had an offensive foul. It was close. As to the possible loose ball foul, I have nothing.