I saw the movie back then, but I missed or just forgot the kelp word.
Saw the original 1984 movie. I think it was redone because I the one I’ve seen since doesn’t seem te same. The first one was the real story. The rest is white-washing.
Saul discovered that the oceans had been completely dead for decades, and therefore the claim that Soylent Green was made from kelp was a lie ...