The Secunia figures are a confused mess that can be used to "prove" almost anything.
Microsoft used them to "prove" that Windows/IIS was far more secure than Linux/Apache recently.
This was dissected in Slashdot (as I remember) and shown to be absolute bushwa.
OS X is based on BSD Unix using the Mach kernel - thus intrinsically it's going to be more secure than Windows, though Apple have made some concessions to usability. Being less common that Windows or Linux, OS X has been subject to less analysis and less attacks. Only Darwin, the open-source OS from which OS X is derived has been accessible to bug-hunters and has had much in the way of external scrutiny.
But I'd take George Ou's little conclusions with a bushel of salt if I were you - remember that on Unix style systems you can only affect one user unless you can excalate your privileges to root. So don't dump your Apples in a panic, 'cos that's just what Microsoft would like to scare you into.
Now that OS X on x86 is out and getting more popular, there will be more exploits and more patches. That's the way the software world works folks!