I assume this was another Obama appointee. I.e. pinko America-hater and/or Muslim sympathizer.
Yes. He knew what was coming.
I am assuming Trump at least had a conversation with him and there was a lack of agreement. To fire him just because the union doesn't like him is not a smart move. The union has hated him since day one because he came from outside BP. It isn't like promoting from within has worked always worked out. The stink on David Aguilar from all sorts of ethics matters was really thick.
None of this is really important. What is important is that the incoming guy will take care of business and be able to manage the Patrol's announced expansion.