Are you sure there's no fare different between the orig. tix and the rebooked one? If there is, then the China airline's office or tix counter @ the airport will more than likely charge him for the fare different on top of the rebooking fee (100 Euro?).. or else, the tix will remain cancelled.

Did you ever figure out why did he miss his flight? I'm sure he has a solid reason to miss the flight.. may be a wild night out before he sposed to fly out and ended up overslept ! Good thing that he's fine.

Hope everything goes well.