It's not a straw-man argument. The post would make perfect sense if it were talking about an offline, labor-intensive business. Unpaid development time has nothing to do with cost-of-running-a-business expense. That's a fact. You can say from YOUR point of view it does. But it does not from the business's point of view.

This is like saying that a surgeon can't launch a profitable web business, because the time spent on it will not generate as much profit for him as if he had spent the time practicing surgery.

that's plainly completely false, and the web business can be very much profitable (just not to him.). Just THINK about it.