Observing how people behave around nominal subordinates is not a new trick or one that is gross. It's an interesting data point. This is unusual as rather than a receptionist or security guard, it is someone who doesn't work for the company.

That you think it's impossible to trust someone without formal vetting is really interesting to me. It suggests that formal vetting by Big Corps is useful but knowing someone from a significant number of interactions/conversations is worthless. I don't buy into that at all, I'd argue pretty strongly the inverse is true and vetting is garbage and interpersonal interactions are useful.