Someone who was in the room at the time suggested he shat himself, you can hear it, if it was a fart why clear the room immediately, commited regime figures like wormbrain and "dr" oz are clearly practiced at not reacting to it, there have been rumors for months that he wears adult diapers, seperate rumors last year claim he shat himself at dinner in paris, someone who worked on celebrity apprentice has claimed for years that trump regularly shat himself while taping.

First hand accounts for decades now of him regularly shitting himself, it's not unreasonable to assume that's what he just did, especially with how people around him react