There's no insurance scheme the IRGC can concoct that protects against the US navy hitting your rudder with a 20mm gun.
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.