I think you're blowing this mod thing out of proportion, I could see a lot of people wanting to be mods and signing an NDA if they were asked to simply thinking it applied to the information they see and the standard user doesn't.  Ban reasons comes to mind.

I agree that an NDA for a public forum is questionable but on the other hand I can understand people wanting to be mods and not thinking twice about signing it before the last couple of weeks.  Lots of them probably saw being a mod as an honor (for lack of a better word) at some point, it doesn't mean that they aren't entitled to change their mind or think constructively.