dont want new mod. registrations to have access to main usercp page

[Logician]

The reason they are given access to User CP is so that they can:
a) Unsubscribe from threads, list their subscriptions,
b) Change their technical options like choosing not to receive emails from admins or allow cookies etc.

IMO you dont need to restrict their access there since they cant abuse it in anyway. G-force's code will do the trick (as usual) if you are determined.