Here are some of the tin-hattier theories.
1. He wanted to be invited to Washington Cocktail Parties by the "Liberal Establishment"
2. Horse's head in bed. Have these people ever read or seen The Godfather? It wasn't a generic horse's head in Jack Waltz's (expy for Harry Cohn) bed, it was the head of his prize stud thoroughbred horse, Khartoum. THAT WAS THE POINT! I realize "horse's head in the bed" has become the meme, but for most people, it would be gross and maybe scary, but not the great threat in and of itself.
4. Specifically, a large bribe from the VATICAN BANK!!!
5. Blackmail. (Sexual indiscretion of some kind.)
6. He was a liberal all along. (Thank you, Ann Coulter.)
7. According to Charles Krauthammer-He did it to keep people from saying the Court was too partisan. (He couldn't have done that BEFORE Citizen's United?)
8. He was "setting a trap." This is the Wing-Nut silver lining spin crowd mantra from those who insist that by framing it as a tax, he gave the country the push to rise up en masse and elect Mitt Romney to undo it.
9. He THOUGHT he was setting a trap, but he was really being too clever by half.
10. One of the most disgusting things I've ever heard any Wing-Nut say, and this is up in Virginia Foxx territory: it's because his anti-seizure meds are messing with his brain. (This is actually up on Drudge and being spewed by Michael Savage.)