HCL is an extremely strong acid. Very dangerous to handle. A little spill or splash could be a life long disaster. You would also be required to carefully dilute the brew with enough water in in order to lower the hydronium ion levels. Or it would burn you going down.
With a %28 solution of sodium chlorite I'm quite certain you would have a violent reaction mixing it with HCL unless they were diluted. I'm sure someone would quickly hurt themselves and start screaming bloody murder. With all the opposition to Miracle-Mineral-Supplement because of its already chemical ingredients. just think of the ranting we would have if we were activating it with Hydrochloric Acid!
Even though not all the sodium chlorite is converted it is still mixed with the weak acid and will continue releasing Chlorine Dioxide while in the body. A lot of people don't like the citric acid and use Lemon or Lime drops instead.
They do activate Sodium Chorite with HCL in the water supply as it leaves no residue.