I don't think Iran would do that unless there was already an invasion of Iran underway. And while it might be possible to clear the scuttled ships, it would be extremely difficult and take months, if not years. That would be months or years in which oil supply from not only Iran but Iraq, the UAE, and Saudi Arabia would be choked off. That would be crippling to the world economy.
Just wondering -- wouldn't a couple (or a couple dozen) of well-placed explosive charges disintegrate the ships into small enough pieces and clear the way? Can you expand on the difficulties? It doesn't seem to a layman like it'd be that challenging or take that long. (Then again, I realize little does.)