He makes a solid argument which really comes down to the problem facing any component of an ecology... either keep expanding until you can't... and then die back "involuntarily" (pretty much the universal pattern) or get your act together and make a better plan!

And that's an option only available to "rational" components of an ecology...

So he's really making just a rational argument for the need to either recognize limits or expand the frontier.

Regarding his thoughts on the role of complexity and a society's need to simplify... there's some truth in it but to achieve that solution without the chaos of collapse may actually require an "increase in complexity.