...we argue that a compact worm...appears able to infect almost all vulnerable servers on the Internet in less than thirty seconds.

What's important with respect to taking over the world is the amount and nature of control that can be gained by any given exploit.

Stuxnet was allegedly able to ruin one-fifth of Iran's nuclear centrifuges. Causing such damage is far from taking useful control of important infrastructure. It is not possible to e.g. remote control the Iranian nuclear program in order to build nukes and rockets, which are then remotely launched to take out the Iranian defense capabilities.