... strictly speaking you’re certainly correct that there is still a significant non-food use for linseed and the other vegetable oils. But there were only limited food uses for polyunsaturated oils before deodorization and hydrogenation techniques were figured out in the early-mid 20th century. People might [have] measured out a tablespoon for their cooking pan, whereas today people use these oils prolifically.
I also looked at this website about "Linseed oil market analysis" [1], which shows that Paints & Varnishes is still the largest user of linseed oil. Then processed foods, then pharma, then cosmetic, then flooring (which is probably also as a finish).
I'm eye-balling the graphs because they don't have a table, but it looks like processed foods is only about 20% of the market. That might be a lot, I don't know, but it doesn't seem fair to say all this excess linseed oil is going into foods because there is no other use for it.
1: https://www.grandviewresearch.com/industry-analysis/linseed-...