When people talk about sustainability, they're acknowledging that humans can have an impact on nature, or more to the point, on our ability to sustain our own species. It's pretty fair to say that no matter how royally we mess things up, the biosphere will probably eventually "recover"... it'll simply be drastically different.
So, given that we can be agents of change in nature, it's not unreasonable to consider not only whether we can simply survive as a species, but whether we can or should show restraint with respect to the effects we have on the rest of the natural world.
McCarthy seems to be of the opinion that efforts thus far have been not just ineffective, but actually harmful to ourselves. That is to say, we're better off allowing progress to happen naturally without "artificially" trying to mitigate it. Others would appear to disagree, or at least still consider the pursuit of sustainability, in the popular sense, worthwhile.