> He deliberately took cultivars from his neighbour's plot
You mean stole? Where do you see this in the link you provided?
That's what I read in the article.
> As established in the original Federal Court trial decision, Percy Schmeiser, a canola breeder and grower in Bruno, Saskatchewan, first discovered Roundup-resistant canola in his crops in 1997.[4] He had used Roundup herbicide to clear weeds around power poles and in ditches adjacent to a public road running beside one of his fields, and noticed that some of the canola which had been sprayed had survived. Schmeiser then performed a test by applying Roundup to an additional 3 acres (12,000 m2) to 4 acres (16,000 m2) of the same field. He found that 60% of the canola plants survived. At harvest time, Schmeiser instructed a farmhand to harvest the test field. That seed was stored separately from the rest of the harvest, and used the next year to seed approximately 1,000 acres (4 km²) of canola.