I know we've gone 'round on this a few times. Based purely on the language of the contract, it would be lunacy for IH to pay the third installment. They (IH) are building a world-wide LENR strategy, which is very clear based on their IP angling. Once they had the information from Rossi, that is all they needed. And they got that after the second installment. They need nothing more from Rossi to execute their plan. The contract expressly allows them to make their own improvements and file their own patents. The third payment was never to be paid, and will never be paid. Rossi's mistake. Even if Rossi were to secure a treble damages judgment (which is quite difficult to do, and particularly here where the facts are not clear-cut), then no biggy. A $300 million judgment is inconsequential given that IH would be untied from Rossi and free to market their own wares to the world.
Just to add to this. There is a reason why anyone with actual understand of business and/or contracts would strongly advise again a payment plan that meams that 90 percent of purchase price is paid a year or more after delivery and in particular without any collateral securing the payment and especially not for a granted license that cannot be be revoced because of non-payment (or breach of contract in general). The reason is that such a contract is doomed to end up in litigation over the final payment. This is in particular true where the sum is so large that the litigation cost is easily set-off by even a very modest return interest of the withhold payment.