There likely wasn't. It takes more to incarcerate an individual than pointing to crazy postings on the internet. But, with due process, a GVRO law could have stripped him of his weapons of mass murder.
You assume far too much.
First, you take his guns and piss him off.
You better take his money too, or he'll just go get another. What then?
And you'd better hope you got all his guns in the first place. I know you wouldn't get all of mine. In fact, you wouldn't even get half of mine. more like a quarter, and that's supposing you find em all here, which isn't likely.
And what is there to stop him from waiting the 90 days, getting his guns back, and doing it ANYWAY? What stops him from targeting another gun owner and stealing his guns? If he is willing to step off and kill 20 people, he'll get it done, by hook or by crook.
You aren't making a damn thing better. In fact you are likely to make it worse.
and in the meantime, the new laws will metastasize, and be used as a weapon against citizens.
Foolish nanny state bastards .