The hypothesis correctly anticipated the orbits of Ceres (in the asteroid belt) and Uranus, but failed as a predictor of Neptune's orbit and has since been discredited further.
Then again, I was tongue in cheek regarding Richard "Face on Mars" Hoagland and his, shall we say 'creative' theories about Mars and his hyperdimensional physics.
And we won't even get started about Hoagland's theory that Earth's Moon has a shattered glass dome on it that the Apollo Astronauts photographed.
But Richard was always entertaining to listen to on Art Bell's late night radio program.
Conspiracy theories are entertaining. But if Mitchell didn’t see anything, I’ll go with his pint of view. He was the man on the spot.