For the record, I do not advocate FMJ in a defensive handgun for many of the reasons you all have brought up. But as I said, my buddy seems quite convinced that it is the best choice, and I wanted to see what others thought.
My concern is that his primary consideration seems to be cost. He says he wants to train with the same ammo he carries, and of course who can afford to train with premium defensive ammo all the time? For starters, I doubt many police departments (if any) train with their carry ammo. I know my department didn't. I think you shoot some of your carry ammo, so you know how it shoots, and use training ammo the rest of the time.
I personally would not want to be asked in front of a jury why I chose the ammo I used in a shooting, and have to answer, "because it was cheap."