The robot/bomb solution does seem crude. How far off are we from robots who can get close enough to deploy some non-lethal method of disabling someone similarly armed.
"Safe", no. Better than a bomb, absolutely.
More likely there just wasn't a good shot to take of him, the only question is why not wait him out, and the threats of bombs and the fog of war (and this was much closer to war than any incident in recent memory, it's reminding me of the cultural '60s and those who wouldn't let it go into the cultural '70s) made it reasonable to take a more serious although not necessarily deadly methods (it's not like they used a fragmentation grenade) to stop the threat he potentially still posed.
And given his was a lot better at close quarters combat than his opponents in general (http://bearingarms.com/bob-o/2016/07/08/video-suggests-cop-k...), storming is position is not something I'd ask anyone to do.