I love it when an armchair (or actual) lawyer starts pontificating about stuff. It reveals their heart along with their minds.
In your case, it seems that you are one of those that can't accept the fact that "sh*t happens". Every thing is something's or somebody's fault, and you are not responsible.
That sounds just like somebody (in)famous...
Look if the guy developed some random disease, you could make your argument that he’s just finger pointing to find someone to blame, however this guy developed a very specific condition. One that is WELL KNOWN, DOCUMENTED and UNDERSTOOD to be caused by exposure to chemicals used in microwave popcorn! In fact the condition and its cause are so well connected, if I am not mistake even OSHA has specific prescribed safety protocals for factories manufacturing the stuff just for this issue.
This person clearly developed this condition, and clearly was exposed, without warning to ongoign doses of these chemicals. So to claim the manufacturer is just having its finger pointed as a blame anyone is nonsense.
You don’t have to like the way the legal system works, but it is how it works. There is little way to argue the product wasn’t involved in this disease or condition, and unless he worked in a factory making this stuff, its pretty open and shut the exposure came from the ongoing consumption and use of the product, and like it or not, the company made no warning to consumers of the risk, an risk that they cannot claim they had no knowledge of.