The frigates have [3] 25MM CIWS each alongside sporting sea-sparrow missile systems; useful for point defense of their research and merchant ships.If the civilian vessels are getting hit by missiles or rockets. What is a submarine suppose to do.
The submarine on the other hand is most likely being deployed for patrol and training operations; the conditions currently exhibited in the Black Sea offer a beneficial and rarely seen training environment.
However this is a dangerous move on Turkeys part that may result in some sort of incident between Russian and or Ukrainian forces.