His website also lists "child nudity" as one of his passions, so let's not pretend that we're just talking about some unconventional political beliefs.
Well, we can only speculate. But I would suggest that since the writer themselves is choosing to write an op-ed on the subject, perhaps they themselves have ample motivation to come up with a persuasive word to argue their case? Their goal is to educate normal people on these chemicals and in the piece they explain that the terminology commonly used is so scientific as to be meaningless to the general public. Hence the need for a more direct "forever chemicals" instead of PFAS/per-and polyfluoroalkyl substances, PFOA/Perfluorooctanoic acid or C8/8 carbon chain structure.
I found a couple of news articles crediting the word to this opinion piece (https://www.washingtonpost.com/opinions/these-toxic-chemical...) in the Washington Post by Joseph G. Allen, an assistant professor at the Harvard T.H. Chan School of Public Health and the director of Harvard's Healthy Buildings Program.
What do you mean by spore costs? Wouldn't most large scale farming operations work with liquid cultures based on live mycelium? Liquid cultures are easy to multiply and inject into pasteurized substrate with needles. Once the mycelium has taken over the growing medium, it also no longer needs to be kept in a fully sterile environment.
I'm not at all convinced a pound of mushrooms is worth that much more than pork. Are you sure it's not the meat industry subsidies that are keeping the price down?