Operating a discussion forum has nothing to do with subject matter such as software licensing.  The forum is not source code or intellectual property, and its administrators and moderators have the right to administer and moderate as they see fit.  It's also private property and its owners and management have the right to manage it or dispose of it as they see fit, and also have the right to define the mission and vision of the forums, to update these as needs and circumstances change, and to make administrative decisions consistent with them.  I am not certain why this is even a question.  The MIT/X11 Open Source License has about as much relevance here as the Book of Mormon.