Fletcher would be done for after the concert either way.
I know it would be a his word versus his situation when Neiman would inevitably try to explain to everybody that he didn't get the correct chart from Fletcher. But with their history, I think it would be pretty obvious to anyone looking at the situation that Fletcher had intentionally set up Neiman to ruin his career.
Fletcher had to have known this. Maybe he was near enough to retirement that he figured he could just burn the whole house down to get his revenge?
Less than forget. But more than begun.