> the patent is expired, so the motivation to continue to defend it has waned. If anything, herbicide producers would now benefit if a cheap, public domain chemical were illegitimately banned in favor of more expensive chemicals still under patent protection

That doesn't square with the fact that Monsanto thought it worthwhile to commit scientific fraud to push the narrative that glyphosate is safe, in a scientific paper published the same year that the patent expired.

They had patents on Roundup Ready seeds. Those patents have also now expired.