I believe this question has a factual answer but if mods deem it more appropriate for another forum, so bit.
Is there anything stopping the Acting AG (or actual AG) from ordering Muller to tell them everything he has and then picking up the phone and turning that information over to Trump?
If not, I can see Whitaker doing just that and then resigning under the backlash that is sure to follow. Then Trump can then appoint a permanent AG who starts with a clean slate. You know, just like the mob whacks the hitman once his job is done.
Edit: He wouldn’t even have to resign, come to think of it. Simply stay until a new AG is confirmed.