Regarding whether or not the mission was to kill him... based on the information we've been fed, isn't the answer clearly yes? To accept that they would've taken him alive if possible, wouldn't we also have to also accept that this elite SEAL team was incapable of a non-lethal takedown? Tranquilizer dart, gas, taser, shoot him in the kneecaps, Vulcan neck pinch, whatever. It's not like he took cyanide at the first sign of trouble. They shot him in the head.