> There's an obvious limit to individual output, and his existing employees are probably operating close to that, especially since his business was already under stress.

I'm as big an advocate as anyone for sustainable work practices, and I absolutely agree that most of the time working longer hours is counterproductive over the long term. But isn't working on an assembly line during a crisis pretty much the canonical counterexample? Output scales linearly with time even if you aren't feeling creative/fresh/energetic, and there's an urgent need for more masks now.