His idea is obvious in hindsight, but nobody had thought of it in the 50+ years they'd been using electric fans for ventilation. It's like learning something new in school - once you'd seen it work and gotten your mind past the assumption that the blades in a fan need to be fixed, it's dirt easy to understand and replicate even if you've never seen any internal schematics. Because of poor patent protection in Asia, there were Chinese knockoffs being sold within a year.
It seems to me there are two schools of thought. One is that people have an inherent right to ideas they invent. That's the American dream - to rise from poverty and get rich.
The other is that patents are there to help society, period. In this case, it seems that without patent protection, society was better off with these Chinese knockoffs you mention - let the most competitive production facility win. If he had spent ten years and lots of development resources researching how to build this, there may be a point that society is better off granting him a patent so others aren't discouraged from investing in R&D. However, this argument only holds water in so far that this R&D wouldn't have happened anyway.
The problem with the first school of thought is that it appears the patent system in practice is actually rigged against individuals and small companies.
I personally know one inventor who was basically had no output for 10 years in order to pay off debt he'd accrued because he went out and patented a really good idea for a household appliance - and then never got anything out of it because the manufacturers found another way to build the appliance. Lawyers seem to me to be the only real winners in this game.