It was the dress code that was the problem...
"In order to gain respect in a situation, you must be attired to gain respect," Mr. Adams said in an interview. He said if air marshals were allowed to be too casual in their dress, "they probably would not gain the respect of passengers if a situation were to occur."
"Well, if Allah had intended me to blow up this plane, He surely wouldn't have filled it with surly-looking, crew-cut men wearing suit coats. So I guess I'll just sit back down in my seat here... Geez, Osama is going to be pissed."