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?