Unfortunately, you made it clear you don't own the website. Any penetration you do on a website you do not own without permission is considered illegal. You're no better than those damn hacktivists, and unless you're pulling a jester and taking down AL Qaeda recruitment websites, I'm going to have to disagree with it.
While not trying to minimod, Hackthissite is not allowed to condone or take part of any illegal activity, and we as a website usually frown upon anything illegal. Just because you disagree with a website does not mean you have the right to take it down.
“True hacking is like skydiving, you want to make sure you have arms, because nobody’s going to be there to pull the chute for you.”