"Watchtower did not permit any of the fuel to be used for on-road vehicles, and implemented policies and security procedures—such as securing all tanks and nozzles with keys kept in a secure location, limiting access to the keys, and hiring security guards—to prevent the fuel tanks from being used to fuel anything other than its off-road construction vehicles."
It sounds like they went to extremes to protect their fuel, even hiring security guards. I imagine that wasn't the reason they hired security guards otherwise the cost of protecting their fuel would have been greater than the tax refund.