You need to have Apple-sized leverage to successfully take on knock-off manufacturers in China. He has no leverage.

How much leverage does he need to just get them off Amazon.com?

(a) There's a lot more retailers than just Amazon, and (b) Knock-offs just keep coming back under different brands anyway.

He's been at this for 30 years. If he had early patents, they've expired. If he didn't have patents, he had a product out before the patent and so there's prior art.

The article mentions "His patents are expiring in a few months"