Satoshi gave him access.
That is no valid reason for him to retain access, especially when he practically quit the role that he had.
Self-fulfilling prophesy if access is taken away. Is there a mechanism for taking away such privileges? 95% super-majority consensus, something like that?
No, it isn't. If he wants to contribute, he can create pull requests like everyone else. There is no mechanism for that and if I'm correct, Wladimir is the only one who can do that (due to him being the maintainer of the Github page).