That he made a mistake is much more plausible than that it was aliens. That he was hallucinating is much more plausible than that it was aliens. That he was l

That he made a mistake is much more plausible than that it was aliens. That he was hallucinating is much more plausible than that it was aliens. That he was lying or had a false memory is much more plausible than that it was aliens. Pretty much any mundane explanation is much more plausible than that it was aliens. Extraordinary claims require extraordinary evidence.