This is utter nonsense, as far as I can tell. There simply wouldn’t be enough volatile material to create something that would explode with any amount of force. At best it could turn someone into a walking fireball for a (very) short time, which is bad enough on an airplane, but would hardly bring it down.

It has also been done in fiction. In one of Harry Harrison’s The Stainless Steel Rat books, the hero arranges to be captured, knowing from previous experience that he’ll be stripped as soon as he is. His clothing (no longer inhibited by a chemical applied under his arms) explodes, causing enough chaos that he breaks free and manages to accomplish his goal (I’m kind of hazy on what goal that was, as it has been a long time since I’ve read those books and there were several similar scenes using different methods.)

It made sense in a science-fiction book, where the author could invent an explosive powerful enough to work under those conditions. It makes no sense with today’s technology. Somebody is spreading the rumor for his own purposes, and I suspect his purposes are to sell detectors for such a thing.