For large aerospace projects, the critical decisions are made years before first flight, and most often even years before experimental production start. Judging from the timeline Mullenberg clearly inherited the messy decisions from his predecessor.

Though of course he would have had the knowledge to understand something didn’t smell quite right after. Whether he had the sole authority to order a delay or redesign in the intervening time is questionable. It may have been that he couldn’t wrangle enough support from the board to do something dramatic.