Kasparov has been a none-too-subtle critic of what he considers a thugocracy in the original Russia. But it seems that opposition to opposition has made a viable candidacy untenable, to the point where Kasparov couldn’t even rent meeting space.
At least he didn’t admit to using performance-enhancing drugs during his bout with Anatoly Karpov in 1985.
(He was definitely off the juice against IBM’s Deep Blue—at least in their 1997 match-up. For a fascinating and lawsuit-worthy interpretation of that debacle, I highly recommend Game Over: Kasparov and the Machine. It makes the whole Black Sox scandal of 1919 look positively inspiring.)