"The family farmer who owns this tractor is a friend of mine. He just wanted a better way to fix a minor hydraulic sensor. Every time the sensor blew, the onboard computer would shut the tractor down. It takes a technician at least two days to order the part, get out to the farm, and swap out the sensor. So for two days, Dave’s tractor lies fallow. And so do his fields.
Dave asked me if there was some way to bypass a bum sensor while waiting for the repairman to show up. But fixing Dave’s sensor problem required fiddling around in the tractor’s highly proprietary computer system—the tractor’s engine control unit (tECU): the brains behind the agricultural beast."
Source: http://www.wired.com/2015/02/new-high-tech-farm-equipment-ni...
So basically, the concerns are very reasonable - operations cannot rely on systems that are put out of commission without a way to fix relatively minor issues on the spot.
While the system is trying to protect the farmer for liability purposes, if that farmer overrides the safe guard, liability shifts. The choice should be with the farmer and not John Deere lawyers.