Ah, this is helpful, as I think it highlights the point of disagreement. If you are of the view that an MLM scheme is legal if there is a "real product" that "might be useful for some people," even if that product is a zero-cost ebook, then I think that this is oversimplistic and you would have to consult a lawyer on it. As I mentioned above, the mere fact that you have a copyright backing a pyramid scheme would not necessarily absolve that scheme of responsibility. My guess is that other factors, such as how you advertise the scheme, would be relevant.