You can certainly plant non-GM seeds from Monsanto, but planting seeds that aren't from Monsanto or one of the other massive seed supply companies will get you into legal trouble because chances are they're contaminated with Roundup Ready soybeans.
If you get it contaminated unintentionally, you won't.
Stop lying. You will get sued anyway, you might just have a better chance of winning.
I'm not lying. Don't call me a liar. Monsanto has the same claim on its website. You can read about the suits on Wikipedia. The suits are also public record. Sue them. Go for it. You'll rake in several hundreds of millions and billions of dollars if you can prove its supposedly blatantly misleading claim.