I'm not a pipeline expert, but I've been doing computers sense the early 90s. You have a pipe. It has pumps and valves. You have a computer that controls it all. The computer gets hacked. UNPLUG THE DAM COMPUTER... and plug in another one. Then restart the pumps. If they are too incompetent to figure out a workaround then get the hell out of the way and let someone else try.
If there is one thing I've learned with computers its that the guy at the console is god. There is no such thing as taking over from a remote location. Anyone that tells you differently has been watching too many movies. Send real actual human beings out the the pumps, unplug the dam computer and just turn the pump on manually. Yeah, a person might have to watch the pressure and flow rates etc rather than the computer. So the hell what. Get the dam gas flowing again morons.
Okay... let's put this in context now. They've hacked the database or bounced off the Unix box into the PLCs etc just like you say, but they don't have root. They've now been discovered because of the ransom. So without root getting rid of them should be far easier. The hackers don't control the routers or the OS. Unplug the dam network cable and remove the problem. Its all software. They don't physically control anything.
Yes I know I'm over simplifying. I don't have time to write a dissertation about systems I'm not an expert on. Or time to become an expert. All I'm saying is an expert... a person who deals with those systems every day should be able to resolve this in days maybe less. If the problem is that the individual boards all need to be checked then you bring in more people to help so it goes faster. ANY problem can be solved.
And that's the crux of my point. Those problems aren't being solved and everything is being drug out has a logical explanation... bureaucrats and politicians are in the way. They won't bring in those extra warm bodies. Etc. Why? Because they want this drug out. The hack becomes an excuse. Its possible the cabal is even behind "the hack". Hell it might have been an inside job. Yeah, I'm making leaps, but isn't it awfully convenient that the states effected are all red states in the SE that all lifted WuFlu restrictions and were expecting hundreds of thousands of travelers to show up on vacation who would need lots of gas?
These people set a virus lose on the world, lied about it, tried to bury treatments for it, used it as cover to hack an election, and you seriously think they are above sabotaging a gas pipeline and using a "hack" as an excuse?