I agree with most of what you are saying, however #2 is likely to be mitigated by his not going on a soylent-only diet. Thus there is a fair chance that many subtle overlooked deficiencies in the product will be masked by the "normal" meals he still eats fairly regularly. In your scurvy example, the minimum level of Vit C required (8-10 mg per day) is far lower than what you get from a typical diet (some 10 times that, apparently), so even if he completely removed it from his product, he'd probably get enough of it from his infrequent non-soylent meals. Though his example of forgetting sulfur is a bit worrying and is evidence against this.