So far, it has proven to be a false issue. I have yet to see a single case where a person used lethal force in a justified shooting where the type of ammo came into play for a criminal charge.
Either you had the right to use lethal force, or you did not. If you did, the type of ammo, handload, factory ball, hollowpoint, or whatever isn't inquestion any more than if you used a handmade baseball bat you lathed yourself for self defense instead of a factory Loiusville slugger.
The main issue most folks have with handloads for self defense is the potential for reliability problems and that is why so many choose factory ammo.
In civil court, anything is fair game. They could claim you used factory loads for better reliability so that you made sure that when you shot the bad guy that you were certain to do him the most harm possible. Go figure.
Ask you buddy to give you specific examples where handload ammo used in defensive shootings has been problematic. Keep in mind that a lot of hunters reload their own ammo and sometimes end up using their hunting rifles and ammo in self defense as that is the only ammo they have on hand. So they have a rifle with a crisp 2# trigger and handload ammo. Your buddy also probably thinks that a light trigger will cause a jury to hang you as well. That is another unproven myth. Once again, either you had the right to use lethal force, or not. The type isn't a salient issue - be it with a gun and handloads, a car where you built the engine from scratch, your own homemade bat, etc.