Hi Sophie,
The OOSB entry for SAP* is the fallback profile for when no other structural profile is found. Even if you activated the BADI (assuming HRBAS00_GET_PROFL), it is still possible that it throws a no_profile_found and in that case the user will get the profile that SAP* has in table OOSB.
I wouldn't suggest deleting the entry. Replacing it with a basic profile like Julius suggested is probably the best idea, but this is only recommended when your BADI logic will return a profile for your background and system users.
Good luck!
Brent