Unfortunately that is the way it works.
If you select hide it will not appear in the registration screen but will appear in the mystuff>Edit Profile
If you select show it will appear as a optional registration field and still appear in the Edit Profile.
If you select require it will be a required field in the registration screen but still appear in the Edit Profile screen. At least in the stock code.
There is no way to hide it completely in both the registration and edit profile screen.
