I don't know what Monsanto did or didn't do and don't have any particular rooting interest for Monsanto, but I think it's worth noting that the published science for the carcinogenicity of glyphosate (the "weed killer" we're talking about here) is extremely flimsy.
Most publicity about "cancer" and "Monsanto" is traceable back to an IARC report that the World Health Organization (IARC's parent) essentially retracted. The report itself concerned dozens of different pesticides and herbicides and mentioned glyphosate only in passing. The studies it referred to equivocated about any link between glyphosate and human cancer.
(I'm going from memory here and someone will probably correct me on this, which will be great!)
It would be surprising if glyphosate turned out to be toxic, because it straightforwardly targets a metabolic pathway that plants have and the entire kingdom of Animalia lacks.
California recently added glyphosate to its list of chemicals that it's required to alert consumers about. But of course, that list is long and includes substances that virtually nobody controls their own exposure to, such as acrylamide --- a known human carcinogen --- which is universally present in cooked foods.
Finally, and this is obvious, but we're reading articles on a plaintiff lawyer's website. That's fine, but you're clearly not going to get the whole story from them. For instance, the lawyers are happy to leave you with a headline about Monsanto trying to "retract a cancer study". But they're of course going to leave out the fact that the study in question was the Séralini study, of "Séralini affair" fame; you can look this up in Wikipedia to see what I'm referring to.