It shouldn't be hard to sit for a moment and think of some people who would certainly like for there not to be a treatment consisting of ~$3-5 worth of off-the-shelf, completely unpatentable medicines and vitamins.

There are absolutely some powerful vested interests in not seeing an easy treatment for this disease, or, by the same logic, pretty much any other disease either since there's nothing special about this one. (A not infrequent complaint on Hacker News.) I can't prove they're driving the discourse on treatment for COVID-19, but it sure isn't disproved by what I see happening out there.