Huh? Turkey has the right but not the obligation to close the straits in times of war. And they exercised that right:

> Around February 27–28, Turkey refused permission for 3 of 4 Russian warships to enter the Black Sea, as 3 did not have a home base in the Black Sea.

There's a subtle difference. The straits weren't "closed", one of the Russian ships was allowed passage because its home port was registered as Sevastopol prior to the present conflict.

"pursuant to the terms of the agreement, Turkey cannot block Russian warships based in the Black Sea from returning to their registered base."

I don't understand what point you are trying to make. Are you saying Turkey should have gone against the rules based international order and blocked Black Sea based ships?

Turkey was under no obligation to do anything. Yet they closed the straits to Russian ships to the extent that they possibly could.