I agree, they really should allow people to remove their names. Especially since it's about a personal attack, it's understandable that some people may not want to be part of it anymore after they think it through and maybe they looked up some of the details and find they cannot really stand behind that.
If they really don't allow names to be removed, I hope someone will have the guts to say publicly "I signed not knowing this and that, now I want my name removed".