> The right of free speech is not wholly encompassed by the First Amendment to the United States Constitution.

And there are other human rights besides the right to free speech, which have to be balanced. One of them is the right to safe travel. That means people who are responsible for the safety of a planeload of people have to err very strongly on the side of being safe rather than sorry. And mature adults are suppposed to recognize that fact and not insist on exercising their free speech right everywhere they go, to the detriment of other rights.