But cross polinated beans, if such things occur, would contain DNA unique from the patented Monsanto product.
Unfortunately, that's not how it works. The patent is on the gene, not be bean. If the gene is present in your bean, then you violate the patent -- at least that's Monsanto's position. The counter position is that the patent applies to the beans you buy from Monsanto, but not the beans you buy from someone who grew more beans from the original. The problem with that is that makes Monsanto's IP worthless. If any GMO product is only one generation from becoming "not IP" then you can't recover your research outlay.
So, think about this: let's say you like the iPhone and you make an exact copy. Did you violate Apple's IP? Yes. But what if the iPhone had a mode that allowed you to make another iPhone? We'll call the original the parent and the new one the child. Obviously, Apple's patents and so forth apply to the parent iPhone. Do they apply to the child? What if Apple placed restrictions on what you could do with the child? Like, you could use the child iPhone only as a backup if you broke the parent, and you were forbidden to create a "grandchild" iPhone. Do they have the authority to do that?
There are lots of things you can buy that make things. For example, you can make bread with a breadmaker, and the company that made the breadmaker has no say over what kind of bread you can make or what you can do with it. The tricky questions arise with products that replicate copies of themselves.
Then allowing their gene into the wild to “infect” a non-Monsanto crop disallowing it’s use by a non-customer of his use of seed crop constitute a taking by Monsanto.