Two axioms come to mind:
1. You can't fix stupid.
2. You can make most anything fool-proof but you can't make it damn-fool proof.
This was a case of a man acting as if he was armed and ready to shoot cops - while there may be after-the-fact solutions, one can't expect a cop to just stand there and wait for the bullet - or to allow a potential bullet being sent after regular civilians.
The sad thing is that we have gone from law and order to "give the bad guys some leeway to do damage. If we went back to the 'olden times" where looting/mayhem/arson/destruction of property were valid shoot situations, there would be a whole lot less of the terrible situations going on in fairly short order and more humane actions on others might become viable again.
Agree with a number of your points, on the other hand, Nuclear security is somewhat tied to fixing stupid and Fool Proof. Over perhaps 70 years our procedures have sustained an admirable safety record despite the number of weapons and the armed nineteen year olds on the front line of protection. The same can be done dealing with the public. Shooting situations should be reserved for submarines and the US Navy. Ok, there are going to be situations, but like abortion they should be few and far between. Just consider how that would work if the police were not carrying. In that case the good might suffer more than the bad.
Bottom line, killing of civilians unable to protect themselves, unrestricted swat assaults on the wrong address resulting in death, and all other deadly force incidents that need and can be avoided, must be or we face public outcry that will not go unanswered.