capable != required
If he seriously proposes to help and is told to stick it where he hurts, he can choose whether or not to respond with 'tact and self control' but he isn't required to.
The diver is the one without tact and self control, but you slag elon for responding in kind instead of the diver. You expect more from musk but musk owes you nothing - not even tact. He doesn't have to accept abuse from someone else out of fear of losing your good opinion. It literally doesn't matter to him at all.