It is a remote control, but a case could be made that even though the prince had the phone with him, someone did it from his computer [ Of course assuming he was not looking at his phone at that time. ]
If you're thinking of a private actor, I think that once you have access to MBS phone, you run to Doha before attacking Bezos. Qatar would pay a ton of money for that access.
If you're thinking of a state actor except Saudi Arabia, I think there would be much easier and more discreet vectors to Jeff Bezos Whatsapp than MBS phone (literally almost any of Bezos other contacts would be less risky).
I am not on prince's side, just saying ...