I understand where you might be under non-disclosure, but are you sure the questioner is? Unless you happen to work with the questioner, I can't understand how you'd know for sure they are covered by an NDA.
Companies aren't always properly consistent with their NDAs - they may be really good about keeping distributors under NDA, for instance, while not remembering to do the same for a contractor.
Also, it's not uncommon for sales team people to let things slip that they shouldn't.
All I'm saying is that there's lots of ways that someone could get certain information, even if the company didn't mean to release it. If you are under NDA, then you can't discuss it (in other words, you can't answer the question), but that might not mean THEY can't discuss it.
I'd say that no such reason should be listed because the number of times where the person voting can be sure of the questioner's NDA status is going to be vanishingly small.