They would only do that if it looked like war was imminent - if they closed it before then it would seriously annoy the Chinese, it would put the Arab nations even more in the camp of the West and it would put a big hole in their own pocket. They probably wouldnt be able to close it after the war starts.
Disagree. If they wanted to it would require substantial effort and potential loss of life for us to truly re-open it. You think scud TEL hunts are hard? Try finding ASCM launchers in 30,000 square miles of defended territory. Do you people are going to risk tankers if there is a chance of a hit? And escorting them with aegis ships for defense is going to be tough given the short reaction times at those ranges.
And that is they wanted to do it kineticly...high strength cables suspended from submerged floats could be strung in multiple places and done so quickly...and would be a bitch to remove, especially under fire. Mot ULCC's are single screwed, and it doesn't take much to take one out.
Even more to the point, Iran has a few kilo class modern diesel electric subs...I wrote an analysis paper on how hard it would be to sanitize the gulf shipping lanes of those guys? After talking to a bunch of submariners and running all the detection numbers...it's damn hard given the acoustics of the area (and all the submerged crap preventing good MAD detections).