The bad guy does not play by the rules and for the most part that is what makes him a bad guy!
At this point he has no value to society!
From this point on going through the process and giving him his rights (trial) will probably cost us more than this guy will ever contribute!
That said, in order for the cops and society to be the good guys, the cops have to play by the rules. They have to respond to the situation presented. What unfolds in the final seconds will be guessed and second guessed for eternity. This situation could have been ended with one well placed shot but the whole world would have all the time in the world to form an opinion on that shot.
The cops are in a dammed if they do and damned if they don't situation and even after the final inquiry that probably would exonerate the cops there would be many that would feel the system was rigged in favor of the cops.
There was a choice here between life and death and who knows what choice the bad guy made, but I know that at least one cop made a choice. This situation ended without death.