Secondly we have come a VERY LONG WAY in Science and medicine since the 1930s.
And yes, plants need potassium. They also need phosphorus and nitrogen, along with a long list of other nutrients. As far as soil pH goes that all depends on the plant. Some plants such as fruit trees will actually develop chlorosis and die if their soil becomes alkaline. So the plant studies really prove nothing.
As for the human studies there needs to be a review as to what is really going on. Did the HCl form a new salt with the potassium salt? Hard to say since the type of potassium is not mentioned. What was the purpose of the HCl when he claims that there was already excess hydrogen to begin with? Did the hydrochloric acid orally help with nutrient absorption since many people are HCl deficient? By the IV route was the HCl killing the cancer pathogens? This study could actually back what I have been saying all this time.