Problem: the term "folk linguistics" strikes me as insulting and maybe something invented by linguists to explain how non-linguists have dumb, nonscientific ideas about language.
Other problem: "language ideology" seems bad too, because "ideology" implies a kind of Marxist "false consciousness" which also suggests that regular people are dumb to have the beliefs they do about language.
Solution? What do we call "non-professionals'" beliefs about language? Deborah Cameron strikes me as the most reasonable voice on this -- we all have beliefs that some ways of using language is better than others -- but her term, "verbal hygiene", seems too specific/jargony.