You're free to use non GM seeds (or GM from Monsanto's competitors). What's stopping you and other farmers (many of whom do not use GM)?
Edit to add: You can argue that this is a he said, she said. Since Mr. Schmeiser did not use Roundup I find his reasoning that he has no interest in the Monsanto seeds rather convincing.
"the court only considered the GM canola in Schmeiser's 1998 fields, which Schmeiser had intentionally concentrated and planted from his 1997 harvest"