I'm not an expert on the sale of stock in public companies by insiders. But implementing sale instructions after finding a material risk factor and a filing that fails to reveal it looks shady.
(I continue to default to the assumption of sloppiness over bad intent, though even that is harshly punishable, albeit with fines versus jail time.)
[1] https://www.sec.gov/Archives/edgar/data/50863/00000508631700...
[2] https://www.sec.gov/Archives/edgar/data/50863/00011276021703... Explanation 1