As much as I hate BL and the assholes that run it (Elf aside), I hate censorship even more, so I certainly will not be signing this. I do not wish to encourage governments to take down sites on the basis of them containing things that people object to but which do not do any harm to anyone.
Also, honestly, you're wasting your time. No-one is going to care about a petition to take down some little forum in the backwaters of the internet. If you don't like BL, just go somewhere else and discourage people from going there. Don't try to censor them.