You need a license to produce and sell patented technology.

You don’t need a license to use patented technology which you either bought from a third party, was given or has blown onto your land by the wind.

This thread is going in circles. As mentioned a few comments ago, it's clearly not the case that the technology "blown onto your land by the wind". The farmer was intentionally engaging in artificial selection to get plants with roundup ready traits. I can be sympathetic to the claim that a patented program magically appeared on your computer because of random bit-flips, but I can't be sympathetic if you deliberately set up a system to generate bit-flips on your computer in a specific way so as to produce the desired program.

And note that this farmer would not have successfully obtained glyphosate resistant plants just by spraying his field, in the absence of the contamination. If it were that easy, GMOs wouldn't have been necessary in the first place.