As annoying as it may be if someone self-moderates a thread you don't have to post in it and if you don't like their actions you are free to create your own thread in response. You can be banned from repeatedly posting in a self-modded thread when you have been asked not to so be careful with that.
Are you sure about this? I don't think anyone actually has the authority to tell you not to post in their thread (with the exception of 'local rules' which must be made when the OP was made), however local rules would likely not be implemented in self moderated threads because they are well self moderated