Sorry if that complicates the "Noble Farmer vs. Evil Corporation" black-and-white narrative.
No, it just turns it into a slightly-scummy underdog versus one of the greatest hives of evil in the world. Monsanto has claimed it literally does not matter how their seed ends up in a farm, or if it is being used in any way whatsoever, they will still sue for patent infringement merely by it being present without being purchased. Lookup Monsanto Canada Inc. v. Schmeiser if you don't believe me. For comparison, this would be like (not just kind of similar, but almost exactly the same as) suing someone for copyright infringement after finding a copy of your virus on their system, which they did not put there, and then winning.
No, it's more like Apple making an iPad 3 that makes copies of itself that walk into your lap and turn on.
Are farmers supposed to do an analysis of every plant to verify that it isn't someone elses?