Irrelevant. The issue is whether a small install base of software (an OS is software) will prevent malware writers from taking interest in and exploiting that software. If they'll look at 12,000 ISS products and say "I'm going to take the time and effort to write malware for this," they're definitely going to do the same for 50+ million installs of OS X. And they have. They just haven't been very successful.
There you go again changing the facts and issues. You posted self-replicating viruses. Which means they can just run from one machine and then attach and then spread like wildfire. Then you admit the issue is over malware which Mac does have malware that does exist today and they even block it from the OS level once they find out about it with the built-in anti-malware software.
So quit trying to change the meaning of the words you use to suit your argument du jour. Let's focus on each point.
1) Name one self-replicating virus on windows 7 2) Show me one malware virus requiring user interaction that targets a tiny install base that was widely spread.