I do actually have thoughts on this specific encounter. I find it incredibly interesting, and I do not believe it was a shared hallucination or delusion. It's a feasibly real story, but if you want to dig into the theories, there's two that I personally find interesting. The clown could be a mentally disordered individual (lived away from people, wore a costume for comfort, was generally avoidant and shy, spoke in a non-traditional way) or an extraterrestrial being (strange habits, scared of humans, particularly odd noises, never seen again, strange living situation, etc). Not entirely sure if "alien" is the word that I'd use to describe Sam... I would rather use something akin to cryptid. Either way, a neat case.