I don't know where that info comes from, as far as it being reinstated on the 5th, but if I had had to take a guess as to the purpose of that, it would be that they still want to keep some things under wraps until release, things that may be added after the 5th.
No one ever said the NDA would be reinstated on the 5th, actually. But there might be different clauses to the NDA which detail what can be revealed when... Or different builds with different NDAs.
As was said, the PS3 testers were most likely not presented with the same contract as the press; I assume they're working on a
live build of BrinkPS3 - or very close to - to help iron out the most recent bugs, whereas the press is presented with whatever build/features the devs want to show them...
The various contracts could also have different clauses preventing some information from being revealed too soon. For example, maybe anything related to gameplay can be revealed on the 28th yet no information regarding plot or storyline is to be revealed before release (just an educated guess here)...