I don't think this is an especially good article, and I don't much like the term "viral" in this context since it seems to be being used for propaganda purposes.

There's no reason why businesses can't use software under copyleft licenses. The copyleft licenses are intended to ensure that systems produced for the public always remain available to the public and don't get turned into closed secret systems available only to the privileged. In economics terms it's a kind of free rider problem - how to stop a common resource from being parasitised.