I have it on good authority that they're weeks away from having a nuclear weapon.
The knowledge that western domination over the world is crumbling, that neolibarlism is becoming discredited, and that the capitalist system is imploding. Meanwhile, there's plenty of positive news coming out China every day. China is building infrastructure, transitioning off fossil fuels, and improving the standard of living for its people. China is showing what an alternative cooperative model of development looks like, one that's not based on constant war and exploitation.
Iran could enforce selective closing very easily because they can shoot across the strait from the coast. It's a mountainous region where Iran has a bunch of missile installations which would be very difficult to dislodge. Iran can also trivially enforce a full closing because the strait is very shallow. All they'd have to do would be to scuttle a couple of corvettes there, and it would be completely impassible. Full closure would be the nuclear option.
the original story is that he is illustrating his powerlessness