Imagine that you are an Iranian official involved in the negotiations with the US. You know your country has already demonstrated the will and the ability to close the Strait of Hormuz. That will not change whether you make a deal to keep the Strait open or not. You also know that the Americans do not have a way to enforce an agreement keeping the Strait open at any reasonable cost. Finally, you may readily assume that the entire world will do its best to find alternative routes for goods if the war continues and the Strait remains closed, which will damage your best source of leverage in the long run.
Under those circumstances, wouldn’t it make perfect sense to concede the point in exchange for something of value instead of continuing to endure American bombing and economic pressure? It certainly does to me.