I think it would be impossible to completely isolate them. Even if you completely air-gap all the computers in the plant, still the workers carry internet-conne

I think it would be impossible to completely isolate them. Even if you completely air-gap all the computers in the plant, still the workers carry internet-connected phones. Even if you ban those, the staff can still become target of disinformation when out of work. Maybe the best approach is to just keep it connected, acknowledging the fact that they are potential targets, and then applying sufficient security on all information channels, technological or human.