Well I read somewhere that they did interview some people that voted for Alvin Greene. At least one of them said that the reason they voted for him was because his name sounded like the famous singer Al Green.
I think Xantar's theory is the most plausible "conspiracy" type theory, but if someone did hack the machines to make a point I think the tamperer would have revealed the hoax by now. Unless the perpetrator reveals their act, I'm not seeing how any point is being made... unless the hacker is waiting to have Greene unseat DeMint through nefarious means...