I've been thinking of that very James Woods incident as I read this thread. However, I suspect the man mouthing the word "No" might have been the same one that carried his cell phone into the lav. He may have been checking for a "Go" signal. Perhaps it was a dry run, but in the sense that the participants thought it could be the real thing.
I find this very disturbing. I hope that the flight crew & air marshalls thoroughly checked the lavs during the flight to make sure nothing was being assembled, then left for the next person to add-on. Of course, it's possible that they were assembling something & then carrying it back to their seats.
As to profiling, I am reminded of something Walter Williams(?) once said. Paraphrasing:
I don't think it's unreasonable for anyone, white or black, to be apprehensive about a gang of young black men on a dark street. I'd be apprehensive about meeting a tiger. I know that not all tigers attack, and probably this one won't. But I know that some tigers attack and possibly this one might.