A suggestion for him might be to use a carblower and blow off as much water as possible before he goes in and dries. I'm not sure if it is the coating, just because even a coating like CeramicPro should have no effect on streaks on it or not. To be honest, the only way to tell at this point if he has the trunk polished and replaced with a more reputable coating and see what it does. I can say out of all the coatings I've played with, I haven't seen anything like this and I've used everything from GTechniq to Cquartz, to some of the more "exotic" ones like Kamikaze. Best thing I can suggest at this point is to perhaps get him something like CarPro eraser or Gyeon Prep to use as a drying aid. High alcohol content, good lubrication and doesn't do anything to the coating basically. I generally do like to use CarPro Eraser as a drying aid if I'm using a 2 bucket wash on a coated car.