Real-life sales section just says "Contraband" is not allowed to be sold, it doesn't mention seeds. Justify your case to Richard why you should be able to sell them and he just might let you
Well, the seeds are not really drugs and are allowed to be shipped to just about any country. I think Sythe is in no way responsible for what people do with purchased goods (people can also buy views to spread a virus via a youtube video for instance).