How does this actually work, in practice? If you have read access to sensors, then there's a non-air-gapped network between the control systems and the internet.
If your network isn't air gapped, then it's vulnerable, and attackers will side step the "read only" path to affect control system changes.
If your network isn't air gapped, then it's vulnerable, and attackers will side step the "read only" path to affect control system changes.