I also don't buy your argument that it's nonviolent. By DDoSing a site, your interfering in the legal activity of the target and some outside party. Apply that same principle to the real world and you suggest that it's perfectly reasonable for someone to trespass into a commercial establishment, obstruct the interactions of patrons with staff, and otherwise use resources that are set aside for paying customers.
Since I depend on the availability of these sites, I'm not so enamored with folks who interrupt MY work just for laughs. I'm doubly irritated with people who call it "justified". That smacks of one-sided righteousness and anarchy.
If you believe in your cause, show your face. Make your case.