I found the Macworld article to be rather amusing:
Wow, what are the chances that an anti-virus software maker would want to claim it's a virus?
I'm reminded of Symantec's dubious report on the state of Mac security, which was released a few months ago in an obvious attempt to stir up sales for their own anti-virus software products.
That said, it's only a matter of time before someone releases a real virus on OS X, especially if Macs keep gaining market share. But unlike Windows, OS X was built from the ground up with security in mind, so I'm not overly worried, and I'm certainly not going to throw down 10000 yen for an unnecessary anti-virus program. If you're stupid enough to ignore the warning that Safari gives you, and then go as far as to enter your master password to view a file which is supposed to be a jpg, you probably deserve to be infected!