I don’t think that’s a bad idea. Like Tabata front or goblet squats after leg day, or Tabata Z press after upperbody.
With all due respect to Dan John, Tabata front squats are not Tabatas. They are not a substitute for a bike. On the bike, for example, you pedal as fast as you can. You can’t squat like that because you have to continuously slow yourself down, or decelerate. If you were to do an honest, all out effort, with squats you’re done after one set.
And John only did it once a month I believe.