I mean look at the warnings on what is basically the next step, TPN http://www.merckmanuals.com/professional/nutritional_disorde... . He is basically drinking almost exactly this. Look at all those scary scary warnings. Some of them are IV dependent, but things like "Metabolic bone disease, or bone demineralization (osteoporosis or osteomalacia), develops in some patients given TPN for > 3 mo. The mechanism is unknown. Advanced disease can cause severe periarticular, lower-extremity, and back pain. Temporarily or permanently stopping TPN is the only known treatment." and such are probably some odd nutrient problems.
Any nutritionist will tell you that there just isn't a great long term complete meal replacement. If this guy has one that is great, but he has done nothing to prove it yet. I mean he isn't even completely replacing meals, and has only been doing it for 6 weeks. Which is shorter than some people have done entirely cabbage based diets. Heck he could have subsisted on beer for this long. ( http://blogs.menshealth.com/health-headlines/the-beer-diet/2... )
It is sort of like some blog post claiming to have solved scaling and not actually had any real workload. I mean sure it doesn't look completely broken at a glance, but it hasn't been shown to even work yet. Come back in a year or two when you've dealt with some load (or merely a couple years of drinking the same thing in this case).