He's close friends with many on the board, so they back him at every turn. The shareholders can't do anything when the board doesn't care what they have to say.
Well yeah, but I really expected more out of them. They basically wrote a letter saying "please resign", Bob said "no", and then they said "oh okay, we have no further questions or statements at this time". Again, it reads to me like the majority of people are covering it up for financial/social benefit, or just completely disinterested in resolving their issues.
If we ignore that Kotick probably has build himself a very comfortable nest there and is probably surrounded by supporters I believe that even if they wanted him gone there is probably a calculation lying around in the offices of a number of people that compares Koticks exit package vs. the immediate expected losses from the current damage to the brand (which probably ignores longtime effects, or expects things to just blow over).