It depends on the product and the price really.
He is 5 years too late to make lots of easy money in web design, yes. 5 years ago web firms were able to wow non-technical companies with simple websites and charge silly money for their services. There's not so much of that now, but there are still plenty of companies looking for a new website, or for a re-build of an existing one.
If the site-building system is any good, and if the price is good, it may be worth a go. Have you got any sample URLs and an idea of cost?
Anyway, saying that, I'd be very careful of "patent pending" technology. There are plenty of tried and tested systems which do the same thing.