Did you miss the part about contraband? You quoted it, after all.

Firing on neutral shipping is not the same as intercepting it and inspecting it for war materiel or other contraband. Preventing shipping from reaching or leaving Kuwaiti ports is not the same as inspecting it for war materiel or other contraband.

Iran has been requiring shipping to submit to inspection and tolls via an adjusted route through the strait. And they can certainly deem oil contraband if they are allowed to do food and medicine, as quoted.

Ships that don’t stop get fired upon. That’s what happens in a blockade.

Kuwait is a US ally and hosts American military bases. Stopping shipping to there is very clearly legitimate.