While a good idea, it does not address the mass killings problems we have had. It addresses crime, not lunatics of all kinds.
So, while Obama's right to do it, he is not addressing the problem. The problem is inciting idiots of all knds over the internet to commit murder and criminal acts for bullshit reasons.
The way to solve those is far more complex, and there is no hope for us all with the kinds of asshats some of us have sent to Congress, which is why "arming oneself" is passed around lke candy. It's a cop out. Bullshit for the lame brained. A stupid and perhaps dangerous placebo.