It certainly is. Macs don't need anti-viral ware... as of this time the total number of Viruses for Mac OS X in the wild, after ten years of OS X being in the wild, is ZERO. The business would not have lost a week of productivity due to viral infection if they had a Mac in that location. EVERYTHING that was being done on that computer could just as easily be done on a Mac... and even the Windows vertical solution database they run the optometry Office software on, being that it does not have to connect to the internet, could be run in a virtual machine sandbox under OS X, and be safe. All other work, especially internet ordering etc., could be handled by the Mac side... and be safely done without the need for cycle eating anti-anything ware.
Oh man, you just cannot be that dumb... I mean, I know you're an Apple zealot, but that's just a bald-faced lie. There's been OSX viruses and trojans since 2006, at least.