Limited-use thread?

I'm getting the following message instead of an "Add post" button at the bottom of every thread I read:

Now, "limited use" — in the case of certain huge, very active threads like Fetishes or Meet the Tropers — sounds like Blatant Lies to me, so I'm wondering if there's a site bug or something. Especially considering the last part of the message... people who have been suspended are the last folks the mods want adding new posts usually, so why would they be the only ones with the option to do it in this case?

Someone please explain this situation to me. Thanks.

It's a site bug, which is fixed now. The Edit Banned thread now is limited-use. Only suspended tropers and mods can post in it. Which honestly dials down the entertainment factor of Edit Banned a little bit, but I suppose we must all make compromises for the greater good. :p