Define 'interfere' and 'safe passage'. Are you saying they wouldn't have the right to inspect such ships for explosives before they entered the Strait? If they can't then can they demand that somebody do things like a quick hull inspection before the ships enter the straits. One ship damaged would close the straits down not Iran's problem if those delays cause crude to jump $50/bbl, or more depending how long it goes on.
So far nobody has mentioned any oil for food program for the children of Iran, is the farce of kindness being lifted as the true results of the effects of the program in Iraq are now well known, it was a way to bring war down on the least able to defend themselves, just like it was intended to do from the beginning.