Ask him if he were the President, the Commander in Chief of our military and saw that war was coming, necessary for whatever reason; if it was HIS job to lead our military and WIN, wouldn't he start the war with a false flag?
Wouldn't he want to start the war on HIS timeline and with the support of the population behind him? Tell him that's why most wars start with false flags and stand down false flags. The stand down is easier to understand. (public support) You may want to start there rather than going straight to; 9/11 was an inside job! :)
Good luck. Don't worry, because when he figures it out, he'll be asking to borrow your tinfoil hat.