And no, your kind does NOT believe in responsible ownership of firearms, you just demonstrated that. Until ridiculously unnecessary firearms are banned you will see that incidences like this are only the beginning. The media coverage and outcry in society are pure orgasms to those with legal access to assault rifles and the intend to harm.
So if a guy jokes about being affiliated with terrorists, but really isn't, even though we are at war with said terrorists, he should still have the right to bear? Hmmm. Even if he is just joking, he's just demonstrated enough stupidity about such things to question his rationality to own firearms, IMO. And yet, everyone else should still make sacrifices because of either his possible affiliations or sympathies (self proclaimed, remember?) to those who would harm us, or his plain stupidity?
I believe in responsible ownership, regardless of capacity. I've said so a thousand times in this forum. I don't consider joking about terror, especially after events over the last several years, a responsible action, do you? And in this case, he wasn't joking.
How would you reduce or eradicate the weapons already in possession after banning them?