They got pressured into closing down by the powers that be and more exchanges will be following soon.
Mt.Gox has been able to avoid this so far because they are based in Japan. Plans are in place to get them shut down as well, it's just taking longer than they would like.
I could care less about proof, but can you at least make the story more believable? A good sound conspiracy theory has at least some reference to some kind of specifics. Powerful people paid by.. government? Private person? What could have possibly been in that NDA? What was ExchB doing that the others are or were not?
~weex could pop up and say that this is utter bullshit if he wanted to. It would be unlikely that he would be obligated under the 'top secret NDA' to actively defend the 'conspiricy'. Though possible I suppose, especially if there were some kicker involved.
If I were in his shoes, however, I would stay mum and try to derive some enjoyment out of whatever whacky theories crop up.