Hackers have figured out how a farmer can take control of the computers in many John Deere tractors.

It is true that "malicious actors" could also use these jailbreaks to take control of the tractor. But don't exaggerate the significance of that danger! These tractors have been under the control of a malicious actor (named John Deere) ever since they left the factory.

Farmers, like motorists and other computer users, are entitled to full control over their computers.

John Deere has done various secondary bad things that add to the basic wrong. This includes bad development practices and GPL violations. In addition, its security against unknown third parties is ineffective.