Unfortunately, that is the only thing that works, at least in this country. Moore seems to understand pretty well that the stuffed shirts in the US government and business have all the hacks money can buy to refute or obfuscate any fact produced by their detractors and to produce false facts to their liking. They are pretty well equipped to combat any argument levied against them. What they cannot do, however, is to defend themselves when they are ridiculed and stripped naked of their posturing and false appearances. There is not much they can do when people laugh at them.
Ad hominem? Perhaps - but we live in the times when speech has been so debased by commercial propaganda and political spin that arguments are devoid of any meaning. You can only be rational with those who understand what rationality is. Businessmen and politicians, however, use words and logic the way a drunk uses a lamp post - for support rather than enlightenment. The bastards are determined to keep their position at any cost and whatever it takes and they know darn well what they are doing and what consequences their actions have. Do you really think they will capitulate before facts?
The bastards must be assaulted by any means necessary. Ad hominem and ridicule are the fist step. And it works. Fahrenheit 9/11 was an excellent propaganda film and achieved its goal - it made people curse Bush and Cheyney and if it made at least some of them more resolved to dump them - so much the better.
It also scored a few other valid points that are usually omitted from the "polite" discourse - the class dimension of the US warfare state, the total capitulation of the Democrat Part under Bush assault, and the hypocrisy of the American people in general as demonstrated by their gung-ho attitudes when the war seemed to go well, and the crying and the gnashing of teeth when body bags started coming back home.
Wojtek