You don't need to convince me of the potential malfeasance of US corporate interests - I grew up in West Virginia, a state that's more or less been run by the coal industry for a century. :)

We should always remain vigilant of unappreciated risks, both health and ecological, from existing practices and chemicals. However, scientific studies are not cheap. In a world with an endless supply of serious problems, we have to prioritize research spending on science and engineering that's likely to actually improve life for the most people. Redoing the same experiments we've been doing to death for decades probably isn't the best use of limited science funding from a purely utilitarian standpoint. Industrial agriculture has quite a few more serious public health issues than glyphosate. (e.g. antibiotic abuse in animals)