No. Those static analysis tools don't catch everything. There are relatively well known and somewhat widespread tricks to avoid being caught by them.
There probably hasn't been hardening of it in years and the initial work was probably developed in haste.
This is systemic. Apple has a bad habit of abandoning software that isn't a priority. So, one shouldn't be surprised that Apple hasn't fixed these exploits. And I wonder if the author has fully mined GameKit for exploits yet. Perhaps there are more to be found.
The architecture of iOS and OSX isn't conducive to security AFAIK. It is more of an add-on as one can see instead of being architected in.