The installation of black-market Ukrainian firmware is a potential infosec nightmare. Imagine what a tempting target this would be for Russian intelligence services to backdoor! In the event of open conflict with the United States, they could potentially paralyze a large portion of US agricultural capacity.
Seems like this would require these tractors to have internet connections. Otherwise it wouldn't help much to put a poison pill like this in there because you'd have no way to either activate it at an opportune time, or to not activate it if you don't want to resort to such measures at the current time.
