Make a built-in quality profile non updatable by an end user. These profiles can't be deleted, nor altered, nor restored.
Any attempt to do so by calling any of the following web services should cause an HTTP error 400 :
The web service api/qualityprofiles/restore_built_in must be deprecated and throw always 410 with a clear message.
Actions to delete, rename or restore built-in profiles should be removed from webapp.