What was clear from the lawsuit documents was that they wanted his technology , which is strange if it's so worthless.
That is not strange. They did not realize it was worthless until after they had paid and they tested his devices more carefully. They did not want it after that. They threw it away in the settlement.
They had already begun working with others in the field and possibly transferred some of his IP across.
There was nothing for them to transfer. None of the machines he showed them worked. He told them nothing.
However, suppose hypothetically he had showed them something. Of course they would shared it with others! What else would they do with it? They would have to license it to manufacturers. They cannot manufacture machines themselves. It would have no value unless it is shared. Keeping it secret was never an option. If they could share it with other researchers and make more progress, Rossi would have benefited. So this objection makes no sense.