What's the incentive for a ship captain to risk this? Even if they're more confident than almost everyone else that it's a bluff and think there's a 95% chance Iran does nothing, a 5% chance of you and your crew being incinerated is a crazy risk to take.
Would you go to your normal job tomorrow if someone who has a history of carrying out threats has threatened to kill you for it?
You can't imagine someone who would go to that job simply because the owner hired a bouncer and they have a different faith in authority or really mean looking bouncers than you?
I can spend 10 minutes looking at demographics and tell you the world is not explainable if the measuring stick is my own risk tolerances.