The anti-GMO documentaries I've seen have covered the "their seed blew into my field" and "I bought seed and signed a contract to only sew it one season then breached it" type lawsuits, but not this --
He's buying seed, from a third party, without signing any agreement with Monsanto. That seed isn't even necessarily Monsanto's product, but from plants that descended from those seeds. It may contain the patented genes, but those genes only got there from the original authorized sale of seed to whoever owned the elevator.
The exhaustion doctrine says that a patent holder's rights end at the point of an authorized sale. Once Apple sells you an iPad, you can do whatever you want with that iPad, including selling it to someone else, and aren't infringing the underlying patents the product implements.
So, why can Monsanto claim damages here?