Ultimately, when international law devolves into “might is right”, expect your adversaries to apply the concept as well. Iran has always been the de facto operator of the strait (by fact of being the strongest regional power bordering the strait), and this will remain going forward. Nitpicking how and why Iran is doing this is not going to change the reality on the ground. It is better to spend energy on preventing wars of aggression of this nature from reoccurring :)
So long story short, is it legal for Iran to restrict access to the strait via Omani waters? Nope. Is there a realistic way to prevent it from doing this by force? Also no. Did Iran wake up and decide to arbitrarily take over control of the strait? Absolutely not. Would Iran be willing to revert to pre-war state if their demands are met? Perhaps. Welcome to realpolitik :)
Oh and as far as restricting access via Iranian waters, Iran is mostly adhering to IL because it hasn’t ratified UNCLOS.
> For the record, Oman signed the No Fees/No Tolls pledge with the rest of the EU literally two days ago.
Thanks for the link, but is this pledge binding in any way, or is it just a symbolic gesture? Because my impression so far has been that Oman is willing to play ball.