I might also add I'm a reformed mechanic and automotive engineer. I'm very qualified to do a brake job. But the harmonic vibration at such low speeds doesn't jive with the very low amount of run-out measured at the tire. And the fact that it comes and goes gives me the desire to seek other helpful opinions and not condemnation by unhelpful ones.
I just did the rear brakes on my 2016 silverado, and I had a very violent wobble when I got to 70mph on the freeway. I went home, removed the tire and rotor to see if I had installed it badly. Cleaned the mating surfaces better, and put it back together. Now, it wobbles violently at 30mph. Not sure a bad rotor would cause this.