Considering the effort that Apple marketing has made to make it clear that "Macs" and "PCs" are not the same thing, it would be very difficult to win a case, as Macs clearly don't getinfected by "PC" viruses.
Which is not to say that your stement is wrong - it is surprising that nobody has tried to sue, even if they would almost certainly lose...
Which is not to say that your stement is wrong - it is surprising that nobody has tried to sue, even if they would almost certainly lose...