No matter how many different ways you argue it, Monsanto didn’t create the genes in question – they found them. They did create the technique for inserting them into different organisms, and that technique is patented.
But the idea of patenting the portions of living organisms themselves? That has absolutely nothing to do with the original intent of patent law. Funny how it’s the justices that so often spout fealty to “original intent” who seem the most intent on supporting big ag firms like Monsanto by giving them patented power over life.