I have talked with him about jumping too hard. The 36t engagement ring on the DT hub will help prevent trouble from it, but he still needs to exercise some preventative measures. After this wheel, he's on his own!
When he road my steel frames he would twist them so hard that I had him stop riding them until he got a bike of his own. Last year he got the Caad10 and all is well on the frame front...just the wheels are an issue. Blew spokes left and right with the cheap Shimano wheel. 3 spokes in the first week and a half of riding! Now this. I do believe the answer is going to a non-conventional engagement device.