Page view permissions allow users in allowed roles. We do not have any mechanism for allow all except some specific role. All Users means all users regardless of roles. Selecting a role name like a custom role name means allow that role not disallow it.

If a user is in a role that does not have view permissions on a page then he cannot view the page. But if All Users is allowed then it doesn't matter what other roles are allowed, All Users means all users even unauthenticated users. We have no mechanism for allow all users except for some role.