Good succinct argument for the original intent of tenure and the need for academic freedom. However does it really work? Tenure certainly has often resulted in sinecures. Often mediocre or downright poor professors especially at second and third tier state colleges are there for life and young talent simply cannot be hired. Despite tenure academic freedom has become a relative concept in most universities today. Political correctness has replaced free inquiry and has muted open criticism. If universities were not saddled with this concept, they would be more competitive and dynamic. A tenured professor is much more likely to tolerate the squandering of resources than someone who is competing for those resources. There ought to be better ways to guard against academic discrimination and retribution than giving blanket job security. The practice of tenure at the primary and secondary school level has done far more harm than good. Also there is something inherently wrong to ask taxpayers, most of whom have no such job security, to underwrite tenure.
I agree with you about tenure in the K-12 schools, or for that matter at community colleges or even those four-year colleges where there is no expectation of scholarship or research on the part of the faculty. The point of tenure exists only in a university or a college in which a major part of the faculty’s job description is the conduct of new scholarship and research. Does it still work as designed? Well, I don’t get any grief from my Department Head or colleagues about doing research in the algebraic deformation theory of k-linear pasting diagrams and k-linear monoidal categories, even though there’s no grant money for it and probably a dozen folks world-wide who directly care about my results (though I *can* make a case that there are applications to both physics and other parts of mathematics lots of mathematicians care about). Alan Kors still has his job at Penn, generally a hot-bed of leftism, despite being well-known for his conservative views.
However, you are wrong that tenured faculty do not object to the squandering of resources, we do so loudly and often bitterly at every opportunity. Unfortunately our objections are moot at all but a handful of private universities (mostly in the Ivy League or among other older institutions that modeled themselves on the Ivys) where administrators serve at the pleasure of the faculty. At public universities, the faculty have very little say over the allocation of resources which is handled almost entirely by professional administrators, who as the article notes, without using the phrase, have their own guild interests. For example, most faculty I know, with or without tenure, would be delighted to bounce ill-prepared, lazy students out of the university by failing them, but administrators uniformly want to coddle them and throw great amounts of money at programs to “improve retention”.