If I set up an admin, and turn off their permissions to view IP addresses, they cannot see IP addresses in posts. This works as expected. However, if the admin goes into the admin control panel and searches for a user they can view the user's IP addresses there.
The View IP addresses permission pertains to the IP accessibility features on the front end. In the Admin CP, only admins with the admin permission "Manage users and moderators" can view IP addresses in the Admin CP.