OEF took care of your problem.. do you know how many times he has posted that pic?! Dutifully, he has posted it once again..
LOL... I love poking fun at OEF.. He takes it well, and gives back..
Seriously though.. gripping the pistol too tightly is a problem that I share with your brother.. it feels natural to me, and I have to consciously force myself to relax... another exercise that may help on the issue of the trigger is after firing, have your brother release the trigger slowly until he can hear/feel the trigger reset; then pull the trigger again. This has improved my shooting to a great degree.. My focus is better, and the feel of the trigger seems to be enhanced... Give it a try.