Ah well it's simple then. Now the terrorists know that they aren 't allowed to congregate, nothing will happen. What a relief.
Of course if anybody does congregate, they are clearly terrorists and we can expect to see the sky marshal (well- probably not) stepping in.
It's nonsense. If the threat is real enough for such half-assed measures to be of any use, why is the aircraft in the air in the first place.
The answer is that the US authorities, gripped by paranoia, are clutching at straws.
By the way, wino, what you see here is not America-bashing, as you like to percieve it. It is sensible people completely unable to fathom the increasingly frantic nonsense emanating from your government.
You, on the other hand, accuse non-US airlines of deliberately witholding information vital to the safety of the flight, from the flight crew. If you really believed it was so vital, you might consider sharing it as in all probability, the bad guys already know their own plans.
Of course what will result is the new directive being treated with the derision it deserves, particularly by those who are not American and apparently blind to the sheer lunacy of this stuff...