I, personally love food way too much for this to work for me... I've been working on my diet, and getting to a point where some of my Metabolic Syndrom issues are now getting better (can feel my feet again)... most of that has been from a pretty high fiber, low carb intake. Almost no processed sugars or rich starches (bread/pasta/rice/potatoes). I do have a savory crepe a couple times a week (essentially a low-carb sandwich wrap. I also eat lots of greens, and have been eating 2-3 pieces of fruit a day. It's hard enough not binging out on pasta, let alone only eating a couple times a week.
Billions of people get sick because they don't have a diet varied enogh. Specific, well studied examples abound.
If you want to use some kind of idiosyncratic definition of "sick" that pronounces somewhere between a substantial minority and a majority of the world as "sick" at any given time, I guess I can't stop you. But as a practical matter, we're comparing shake-guy's food to the other foods that people actually eat, not to whatever your idea of the best diet in the world is.
The shake may well not be an optimal awesome diet -- I'd bet it won't be -- but billions of humans survive on non-optimal, awesome diets. The idea that the incredibly varied, constantly evolving, often appalling diets of the whole world all fulfill whatever criteria are necessary for human survival, but that this shake doesn't is magical thinking.
Especially when you consider that -- thread title notwithstanding -- the guy eats a few regular meals a week. What are these magical micronutrients that we don't know about, that are present in sufficient quantities to sustain humans in all traditional diets, but which are needed in such quantities that shake guy isn't going to get them?