After 50 days of a non functional reaction IH would be insane to run the test for any longer. IH could have stopped the test after 50 days.
IH did not want the test in the first place. If they had tried to stop it, they knew Rossi would walk away. By the time the test began they had tested Rossi's devices extensively and they knew that none of them worked. The test was a last-ditch, Hail Mary effort. It did not cost them much. As they said, if there is even a 1% chance left that it might work, why not let Rossi try for a year.