Thanks for the responses. I don't think that having him teach the maneuver would help, he knows the steps to do it just fine.
I'm not his usual instructor, we've been sending him with different instructors a couple times to see if a change of face helped. When I flew with him, it seemed to me that he was tense through the whole flight, though did gradually relax as it progressed.
I say that he doesn't think he's scared, because he talks like he does just fine at them etc. Whether he believes that or is just bluffing I can't tell.
In flight, it's his body language that shows his nerves. He's very tense, and makes jerky control movements, and seems to go into the maneuver with a "well if I really have to" reaction.