He absolutely did recklessly cause his pal to be shot. No robbery, and indeed invasion of someone's home, no-one would have got shot.
Drink drivers don't intend to kill anyone and 999 out of a 1000 don't. But the ones who do get the book flung at them and rightly so; they may not have intended to kill but their reckless actions brought about the circumstances - it's the same here.
The bottom line, cliched but true, is don't do the crime if you can't do the time.
Incidentally, some of the brouhaha about homeowner shootings strikes me as otherworldly - I'm not saying they are right to do what they do, but I do feel that critics seem remarkably insulated at times. Faced with two young thugs, in such circumstances, you've plenty chance of getting kicked to bits, possibly to death.
The whole assumption of over-reaction strikes me as strange - people get brain damaged and killed all the time challenging criminals without an advantage in weaponry - a bloody professional boxer did recently, never mind your average joe. I'm sure there is over reaction in many cases, but I also suspect it's nowhere near as black and white as bleeding hearts would have it.