Earlier quoted context omitted.
> Why THE FUCK are industrial controllers connected to the Internet? Fixed that for you.
Not really, since the control system wasn't connected to the internet. They did, however, rely on "air gap" security, as you appear to be proposing. Defense in depth is the only valid model of protection, but this requires intentional inclusion of cyber security concerns in the design stage of your plant, and on-going maintenance and auditing by a skilled IT team, and training of all your employees against social eng…
Fair. I should have RTFA before commenting.