No, that's a simple observation: why would anyone expend the time and effort to write viruses for an uncommon platform? There's no viruses for my Atari 800XL, either...doesn't mean my Atari's more secure than a Mac, it just means there's no upside to anyone in writing a virus for a machine that only I still run.
And then there's the simple fact that the people who write viruses tend to be superuser-types that absolutely loathe the "accessible to every drooling idiot on the planet" approach Microsoft takes to software development (the !@#$ing dancing paper clip in MS Office, for example...I hate that thing. Most of the non-technical users I know love it. MS targets them, not me) and have their own evangelical reasons for targeting Windows.
And then there's every competent sysadmin I've ever talked to who's worked with Windows boxes, and secured them perfectly. Again, Windows' "bad" security is due in no small part not to the technology but to the user base they target, who don't know the first thing about security. Generally, IT security is incompatible with Microsoft's traditional marketing goal of making software accessible to the public, so MS software tends to be less secure out of the box...because it sells better that way. Microsoft, by their own admission, isn't a tech company, they're a marketing company. And they are VERY good at it. They didn't get 90%+ of the desktop market because Windows is good, they got it because it's more accessible to the average user.
Personally, I don't have a dog in this hunt. I have to use Windows for work (clients run Windows servers. Even my Java- and Oracle-based clients run Windows servers, which is idiotic). I've hated every Mac I've ever used...and if I want to use FreeBSD, I've got three different flavors of Linux at my fingertips right here at my desk. But pretending that Apple's market share has nothing to do with their lack of virus attacks is silly...any half-decent security expert can tell you that security is far less technical than it is psychological, and that basic psychology dictates not wasting your time attacking an uncommon platform rather than the ubiquitous one.