If your speculation is right and they were not allowed to disclose the nature of the deal, then NWBO could have still communicated that more detail was not provided due to an NDA or due to a given regulation or law and in the case of a law or regulation cite the exact regulation or law that applies.
How would providing a reason they can't provide more detail stop speculation? Your comment was:
As usual shareholders are left to speculate due to poor communication.
The two reasons you listed are plausible but it really doesn't matter because it's not poor communication, they just can't tell us the exact reason.