well, did anyone consider this? That Microsoft might go so far as to learn how to prevent the antivirus from fixing,(or blocking) the security holes in all Linuxes in general so that the hacker will eventually try and destroy the credibility that Linux has?? If he is, he is trying to do something that is virtually impossible, due to the high number of variations of Linux distributions. For example: one might try to attack Slackware based distros in general, however it is so customizable that the hacker wsould have to find a specific bug in the kernel, which by the way isn't always the same anyways.
So he would have to make this virus or whatever monstrous in size to accmodate all of the different types. It just would'nt be feasible for a hacker at least.