Staged Hack Causes Generator to Self-Destruct
If they are connected to the network, there is probably a very good reason for it...
Lazyness? Insanely stupid cost cutting?
Yes, the components of the system need to get data back to the dispatcher, and receive instructions in return. No, that doesn't require the internet. You can use a modem on a leased line. Yes, it really is possible to send and receive data without the intarweb.
The internet is a cheap, insecure way to accomplish what should be done on an expensive, secure, private network.