So, you're saying that a person who can't control his emotions in an on-line discussion board is a perfect candidate to own a gun because he has such wonderful control... over his emotions.
I may be wrong, but I think what he is saying is that the internet has no consequences so people that feel ineffective and powerless in real can act without fear of retaliation. These same people may have the necessary facilities to make decision in their everyday lives but the lack of checks and balances online causes them to act out. They may be cautious, maybe even meek, in their daily lives. They might, in reality, be the proverbial 90lb weakling but online they can be the bully.