It's not even just the price of a ship and cargo at risk. Lead times are around 2.8 to 3 yrs for crude tankers and around 3.5 yrs for LNG carriers. That's a long time to not be able to conduct business even if insurance did pay out. It is 100% rational to sit out a few weeks to figure out how to resume operations safely rather than trying to sneak through and hope for the best.

Oddly, due to maritime law, it's the cargo owners who would have to pay if the ship was only damaged but not sunk.

Alternatively wasn't he floating some kind of mandatory insurance scheme? mandatory in the sense that the insurer can't refuse. Sounds like a great time to liquidate some ageing stock for yhuge profits.

Oh it is insurable all right. You just have to pay what is called the "war premium". I bet they wouldn't like what comes through the strait anyway.