I have to say on this point your logic is atrocious. If we have synthetic hamburgers and synthetic fish, then it indeed does not matter from the point of view of Malthusian population limits with respect to food that the majority of life in the ocean is wiped out. It may matter for other reasons, but you haven't stated them.
I feel this is one of those Smooth moments questioning what the definition of "is" is.
If literally all food is synthetic, that indicates it's become entangled into an increasingly complex chain of specialization of labor, so even if you worked in that industry, you would probably not be able to produce it yourself. That would be an extreme far left viewpoint where individuals are all required to fully integrate with the state to exist at all or you just instantly die. As I tried to tell the Anonymizer, technology solely for the sake of technology is useless because it's not a net gain, it creates a dependency to enslave you at the same time.
The ability to become self sufficient, even if you don't exercise it, is far better than piling on endless amounts of unneeded complications into people's lives to entrap them. Am I the only one that doesn't think Ted Kaczynski was completely insane?
Maybe you believe that the ability to become self-sufficient is by definition a desirable outcome, but does not mean that lack of self sufficiency means that Malthusian limits will be reached. The counterexample is exactly what has happened for the last century or so.
Also, in general terms, specialization increases productivity across the spectrum. Even the least productive have cell phones (etc.) today, which means they are far more productive
in absolute rather than relative terms than the least productive in times past. Possibly more than the most productive. You do not understand how gains from trade work.