r0ach stated he is concerned about an insufficient supply of suitable farmland, and the information I linked to pointed out that we can grow food at 10X or more higher densities (on a yield basis) and without pesticides. Note this can be done at scale so not every person has to do it.
It was actually a more complex idea than that. As long as there's abundant sea life and natural wild life (which in the context of humans are basically...resources), then you have the ability to "opt-out" of whatever system tyrannical humans establish. Smooth seems to imply that all of civilization needs to be vertically integrated for maximum efficiency, and it doesn't matter if all the oceans are empty, food is entirely synthetic in a complex chain of labor custody, and every inch of land is covered with concrete. In that instance, there is no opting out of anything, and you are in fact a permanent slave.
Outcomes like this are more likely to occur the higher both population and/or technology increases, and claiming anyone who identifies this fact is a "Malthusian" is ridiculous. You will eventually not be able to opt out of anything, which is why people like Ted Kaczynski are not actually crazy. He did not want to be locked into forced collectivism, so while his actions to try and prevent that might have been dumb or ineffective, the problem he identified is actually real.