Note the shallowness of the waters. It's not the width of the strait, it's the depth of the water that's the threat. Iran could sink a tanker there before anybody could do anything about it. And even if we retaliate, the damage is done........
I get it. I saw the scale of miles and depth charts in your graphic. I am not sure what the draft is on a tanker, but it seems reasonable that the others can circumvent a wrecked one with the available waters. We reflagged Kuwaiti tankers and escorted them in the 80's in response to Iranian threats. Any potentially threatening areas where they have mine-laying vessels or 'Sunburn' type anti-shipping missiles would see immediate attention if hostilities were imminent.