This incident reminds me of the time an investigator interviewed me as part of my roommate’s CIA clearance. Before we started, the investigator asked for directions to the bathroom. When he came back, his fly was unzipped, and without really thinking about it, I told him so. He zipped it up and we got on to the interview. To this day, I’ve never been certain whether it was accidental, or a deliberate ploy to put me at ease.
It would not surprise me in the least if Donald Trump did this deliberately so the media hounds would waste their time chasing after this particular squirrel, distract the media from barking on about the Kavanaugh nomination, and make Trump a more sympathetic figure.