It's a nice PR action for John Deere. Now US farmers know that if Russia invade the US, JD will have their back. But barring a russian invasion, how many tractors are being stolen in the US every year? I don't think this is a real problem.

And we are talking about a state actor here. I am sure that Russia can find a way to bypass the lock and if not, as mentioned in the article, they will sell the parts.

However, if I was a farmer, I wouldn't want JD to have that level of control on my property. I would want JD to handle that control to me, ideally under the form of public and documented API and free software.