So 20% macs have infections on it that they have no reason to counter. Woo.
A stat like how many would actually make it onto a system that would have a reason to guard against that virus would be an important stat to guestimate. If you assume there are hardly any windows machines with rudimentary enough security to accept the majority of these viruses to begin with - a story which would sync with known windows infection rates -, this becomes a nonstory.
But this essential fact wasn't looked at, making this entire story worthless propaganda.