ABAddressBookCopyArrayOfAllPeople is implemented as a direct branch to ABCCopyArrayOfAllPeople. Right after that are the ABAddressBookGetPersonWithRecordID and ABAddressBookGetPersonCountShowingLinks functions and they will be wiped out by the closure generated by MSHookFunction. The proper function to hook is ABCCopyArrayOfAllPeopleInSourceWithSortOrdering. See my similar package for an example: https://github.com/rpetrich/ContactPrivacy
This version is substantially better than mine - in addition to the correct hook mentioned in the parent comment, ryanpetrich's code uses a private CoreFoundation API rather than UIAlert which is both safe to access from non-main threads and blocking, making the tweak both simpler (no dispatch or blocks) and allowing it to pop up a "yes/no" dialog.
I've updated the README in my GitHub repo to point here and I'm considering ContactPrivacy a better replacement for AddressBookPrivacy at this time.
Here's to hoping Apple does something like this in a future release of iOS.
Kudos to beating me to a release.