By letting reporters in his hire just do their jobs, Murdoch probably gets privileged access to a great deal of secrets and speculations. Carreyrou's reporting could very well have persuaded Murdoch not to make further investments in Theranos, thereby saving him billions.
As the rationalists say, if you can explain anything, you can explain nothing.
I'm not saying he did it for good reasons. I'm saying it's plain that nobody here knows why he did it, and lack of knowledge is lack of knowledge, not license to just fill in the blanks with whatever you like. (Our brains are very good at that, and the careful person must be in a constant fight against that tendency.)
But jerf, I already know he's a bad person.
You are justified in using past history to do a certain amount of broad concluding (nothing as specific as the 5+ hypotheses given), yes, but bear in mind you are not justified in "A: Murdoch is bad B: Here's a thing he did C: I bet he did B for a bad reason because A therefore D: Murdoch is even worse than I thought". You are "spending" confidence when you do this, not increasing it. (Another very common cognitive error. Not sure I've seen this on any fallacy lists. Probably needs to be, and given a name.)
I seriously doubt he allowed Carreyrou to continue for the sake of good journalism.