Is your opinion of exaggeration one that comes from being a farmer? Because I know a few farmers, and the fear is real.
The one case referred regarding this (Monsanto vs. Schmeiser) is widely misreported by anti-GMO and anti-Monsanto activists. See Wikipedia:
https://en.wikipedia.org/wiki/Monsanto_Canada_Inc_v_Schmeise...
The case is widely cited or referenced by the anti-GM community in the context of a fear of a company claiming ownership of a farmer’s crop based on the inadvertent presence of GM pollen grain or seed.[21][22] "The court record shows, however, that it was not just a few seeds from a passing truck, but that Mr Schmeiser was growing a crop of 95–98% pure Roundup Ready plants, a commercial level of purity far higher than one would expect from inadvertent or accidental presence."