John was also in the process of deposition for an appeal to a case he already lost in 2019. If Boeing wanted to kill him they would have before the 2019 trial.
And by the time he complained in 2017, both 787 and 737 Max that he was spilling details on had been flying for years. The FAA investigated and found a decent chunk of the issues had already been addressed. So it wasn’t even timely information by the time John spoke up.