Good grief. What on earth is the point of divorcing at 91? Has he changed his FB status to single yet? Or “it’s complicated”.
He should have kept the one who protected him from the pie-thrower.
Money. No doubt he has a prenup.
But their state may have a law whereby you can take against the will if still married.
It could be a prenup thing. Remember Ellen Barkin’s billionaire husband dumped right before she would have come into big money.
I can think of 17.7 billion reasons. Perhaps he just got tired of her putting on Rolling Stones records on his record player. Maybe he no longer needs her for the reasons he originally married her. Maybe she just ticked him off. Maybe Jerry herself got ticked off when he summarily called her a cab.
Maybe he would rather deal with a divorce settlement while he is still alive. Maybe he doesn't want his children having to deal with Jerry Hall after he is gone.

Some people have run marathons at age 91. But I doubt Murdoch is in such good shape.
If I were a super wealthy older guy, I’d just find an attractive and smart young nurse, have her move in, pay her $400k per year to take care of me and provide intelligent conversation, and after 3 years let her move on with her life and get another.
It’s gotta be cheaper than divorce.