Even taking this claim at face value, we would have to solve plant based diet issues, such as insufficiencies in some vitamins (e.g. B12), complexity of getting sufficient amount of essential amino acids ~~(esp. omega-3)~~ and omega-3, slow but steady reduction in an overall amount of nutrients present in both vegetables and fruits etc.
And if we say that the answer is to "engineer" foods: fortify grains with vitamins, come up with "equivalent on paper" diary replacements (e.g. oat "milk") etc, then we need to ask ourselves whether this is actually the answer? Can we effectively reduce foods to a small number of "key ingredients" and add them everywhere? Is this sustainable? What about the environmental impact of running all those factories that "engineer" plant-based alternatives to the foods our ancestors ate for generations?
I do not know the answer, I'm no scientist, nor proponent of any specific way forward. I just read stuff. The only thing that I do believe is that there is no silver bullet.
Books I find very interesting:
UPDATE: Corrected that Omega-3 is indeed not an amino acid
And E2EE is only available on phones, circa a couple of years ago anyways