I would be willing to bet that there were people on that flight who have at one time or another made that same statement and then just sat there paralyzed with fear.
With 9-11 the terrorists violated a social contract. It used to be that in a hi-jacking the terrorists had a beef with one govt or another and there was a good chance that you would simply be inconvenienced for a day or two. that contract is now null and void. Richard Reid was the first to find that out.
One person might feel intimidated, but in a group, an otherwise timid person is going to feel a little more courage. Add in a person or two like me that are a little high strung already, a couple of wannabe heroes, a few athletes aging or not and you have the makings of a little big horn.