It might have helped if he took the OP up on his offer, no?
Except you don't need to be actually making or taking a call for it to be an offence, it's having it in your hand that counts.
By the way the OP said he was resting his head on a hand (singular). I see this quite regularly, particularly in evening traffic!
My mistake I meant hand, not quite obeying the rules of the road no matter how many people do it, but thats off point anyways.