Maybe I'm just cynical but I have to assume someone will test the extent Iran can hold them to a payment if it doesn't want to stop maintaining the terms of the ceasefire to back up the demand?
(Edit- missing negative)
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?
They've blown up several ships so which ship owner will test them? Spend $1m on a transit fee or risk $90m on a new tanker.