Two things.

1. They reflexively think that any health craze is automatically wrong.

2. The US regime has been saying that seed oils are healthy and better than animas fats for 70 years in order to hide inflation and push statins for $billions. So for midwits who are completely demoralized by authoritarianism, seed oil disrespect essentially slays their god, the State. Same for the vaxx, Bitcoin, etc.