Their leader is a complete knob though. But as you say, Black sea and also Turkey is getting paid moolah to keep middle eastern refugees from passing through to the EU, so they are kind of indispensable politically (we only like white Ukrainian refugees after all). Even if he does carry out his veto, as stated above, there'll just be parallel, identical arrangements that exclude Turkey.
And nice mention of the Cuban Missile crisis, which i believe the Soviet union 'lost' by said missiles being withdrawn from Turkey (also known as achieving your objective).