Would it not just be better, if one of the major Anti-virus software companies could start accepting Bitcoin as a payment method for their software and subscription updates? I do not know of ONE of these companies, who accepts Bitcoin. I would switch tomorrow, to a company that accepts Bitcoin for yearly subscriptions.
I have, um, bad news for you: the whole point of the anti-virus software industry was always (and still is) a way of extracting more money out of the typical user. There have been expose's and rumours in the past of anti-virus software companies writing viruses themselves when the natural supply of viruses dries up (and those software companies were always well placed to write their own viruses, as their industry position as "security" experts made it easy to justify getting a source code licence for Windows or OS X).
Moral of the story? Don't use operating systems that "require" anti-virus. If such OS's were half way secure to begin with, viruses would be much, much less common and possess far less capability to cause damage to your computer.