Permissions when person is in multiple teams

We have a team hierarchy:
top
subteam1
subteam2
A person has been added to all 3 of these teams. The permissions for "top" are normally set to be inherited by the subteams.
A permission: Save changeset Links and Comments is default to "deny" at the top, but overridden to "allow" at subteam1 and subteam2.
When the person tries this action, RTC says he doesn't have permission. Setting the permission at the top works. So that's a "work-around" - but I'd rather not give this permission to everyone, but rather just to the members of the subteam1.
My general question: If a person is in multiple teams, and is looking at editing some change set (to add a comment), what is the logic in this kind of situation where there are multiple teams involved, and each team might have conflicting permissions?
When the person tries this action, RTC says he doesn't have permission. Setting the permission at the top works. So that's a "work-around" - but I'd rather not give this permission to everyone, but rather just to the members of the subteam1.
My general question: If a person is in multiple teams, and is looking at editing some change set (to add a comment), what is the logic in this kind of situation where there are multiple teams involved, and each team might have conflicting permissions?