One possibilty could be that they wanted to get the IP as cheap as possible. They made a contract which Rossi felt fair (100 M$ + further license payments). IH got some IP to get COP of ~10 after paying 10 M$.
Then they took the chance to break the contract.
Result: An IP worth billions or trillions of dollars in the future for cheap 10 M$!
The contract break is/was possible because Rossi already has a bad public image as frauder. So everyone would believe IH if they would say something against Rossi's credibility.
Maybe they thought Rossi is a dumb old man, and didn't expect that Rossi was prepared for legal action and collected important data since last summer.
Just my guess. But seems to fit into the big picture and the "please go home, we even will give you X M$" offer.