I always personally thought that rule was kinda stupid since both the CMX Viewer and skin templates are accessible to anyone, licensed or not, but I guess if it falls under the "demo users can only post demo content" part, then okay.
Not gonna lie, I kinda feel bad for demo users on this forum. Wouldn't be surprised if, soon enough, they can't even access the forum anymore, and I've read enough posts to know a lot of people here would actually celebrate if that happened.