Re: Presumably the fuckwits in charge ...
"I have never worked with pipeline systems, but my guess would be that their is some need to extract billing and operating data from the product delivery system and probably some need to input some commands at times. So a completely separate system might be difficult/impractical/impossible"
That pipeline has been in operation for longer than an internet-based control system seems feasible. It has been proven to be operable without exposure to the net. It has now been proven to be inoperable with exposure to the net.
We can, then, eliminate impossible and impractical. Difficult, maybe. Probably an option you left out - inconvenient. But far better than what they've got now.