If it is true that he is dealing with cognitive decline and the response from the rest of the GB is to bury him, I have to think that one of two things must be true:
1. He was one miserable asshole.
OR
2. His fellow GB members are a collection of miserable assholes.
Why not explain that he was stepping down due to health? That would be perfectly reasonable.
I hope that he was pushed out in some sort of power struggle. If the GB are the kind of people who would treat him like this because of mental decline, that is very, very messed up.