Of course, as long as the network is truly isolated, that's a non-issue. But the basic premise is that a machine that can access the Internet will self-replicate everywhere to preserve itself.

After all we've already seen that malicious software can be both highly resilient and able to do real-world damage (e.g., Stuxnet). These come from human intelligence: by definition, a super-human intelligence should be able to achieve all of that and then some.