How about nutjob control instead? That guy should have been in a hospital with a lock on the door.
“Hospital with a lock on the door?”
Why? For how long? What would be the justification: “Not dangerous to self or others today, but he might someday harm unidentified others...because he was a Marine ...white male...or owns a firearm?”
An armed public (even in bars) is a more reasonable and much more effective solution.
There will always be crazies on the loose, especially with the ACLU around. The only thing that will possibly prevent it stop these shootings is the presence of an armed citizen. There is a reason most Antifa activities occur in areas with strict gun control, ditto for loonies looking for victims.