In a press release and a five-page letter to the scientific community, Peter Kim asserts that although Merck had to correct a statistical method, the 18-month conclusion is still valid based upon the data Merck had at the time.
Even if the mismatched income appears correct, re-calculate the proposed tax to be sure the appropriate method has been used and the amount is correct.
So perhaps the predicted trajectories are correct after all, but the flaw lies in the Doppler-ranging method used to measure the probes' actual trajectories.