If it actually works, it’s worth hundreds of billions, maybe trillions of dollars. Why sell for $11 million?
Uh, perhaps because Rossi needed CAPITAL to bring the technology to market, just like any other inventor of a world shaking product. No billions unless you have a few million to get "up and running".
You can bet that Rossi still owns a percentage of the rights, and will receive royalties on each unit sold.
I doubt very highly that they own all of Rossi’s IP. They probably own a certain percentage of it and are going to be giving him royalties for every unit sold.
It’s a little bit like when Bill Gates sold BASIC to MITS. He retained the rights and MITS was obligated to put their best efforts into selling it. That was the lawsuit that Gates won against MITS, because they were not putting their best efforts into it and he was free to sell it to whomever he wanted.