It's your choice to take a congressional speech that references USA Today at face value, but a quick search turns up a GAO report, from 2003, that summarizes over 2000 incidents reported by the Federal Air Marshals, including 444 reports of "Suspicious person", 394 of "Suspicious activities by person", 73 of "Disruptive/disorderly person", 35 of "Medical problems", 28 of "Arrest/detainment by or at request of air marshal", 20 of "Interference with flight crew by passenger" and 19 of "Verbal threats or threatening behavior".
This, over a 2 year period starting in Sept 2001. Perhaps they've done nothing since then.
Pre- Air Marshalls we had all these type of incidents, and they were all satisfactorily dealt with by exicting measures WITHOUT introducing a fire-arm to the aircraft.
