This is utter nonsense.
If she killed the King of Stormwind in a fit of blind rage we'd be having a different story right now.
One where Orgrimmar is destroyed and the Alliance is hunting down Jaina for regicide. Only Jaina wouldn't be much of a raid boss, because she'd probably go down sobbing in despair that she killed one of her good friends and the father of a kid she considers a nephew.
That actually sounds like a much better story.
Indeed I would enjoy this story much more