Military history is full of quotes like "war is too important to be left to the generals". When you put people who focus on technical matters in charge, they often make poor decisions, as they are not looking at the big picture.
The question is not about whether the US can blockade the Hormuz Strait but who gets blamed for the blockade. Iran is messaging that it is making serious attempts to reopen the strait, while China and Russia are probably reinforcing the message. When people around the world suffer from the consequences of the blockade, they are more likely to blame America for their troubles. Or at least that's what Iran is trying to achieve.
The question is not about whether the US can blockade the Hormuz Strait but who gets blamed for the blockade. Iran is messaging that it is making serious attempts to reopen the strait, while China and Russia are probably reinforcing the message. When people around the world suffer from the consequences of the blockade, they are more likely to blame America for their troubles. Or at least that's what Iran is trying to achieve.