Turns out that carrying certain kinds of novels can make you so suspicious that airlines won't let you fly. See this City Paper article for an example.
Granted, it was a little silly of the guy to bring an Edward Abbey book along with him to the airport under the current circumstances. And I can sort of understand the airline's reaction: they were in CYA mode, didn't want anyone to later ask them, "How could you have let that guy fly, given all these warning signs?"
And yet. If they really weren't gonna let him fly, they shouldn't have told his mother that they were.
Also, I'm very skeptical that a real terrorist would bring an Edward Abbey book along on a flight.