What purpose could China have comparable with the escort of ships carrying nuclear waste to England and Plutonium back?
China is opening up huge trade with Africa, South America, and other distant places.
They have tremendous amounts of energy based products, and many, many other products that will be depending on the SLOCs to reach China.
Having a couple of long endurance, long range, large cutters like this will be very valuable in patrolling and safe guarding those SLOCs for anti-piracy and other missions. They will also be very useful in any humanitarian needs, or if needed to assist Chinese nationals abroad. To be able to do this with such a vessel and relieve naval vessels from it would also be valuable.
Those uses, applied to any economic, Chinese citizens, or humanitarian effort makes these cutters very useful for China in any long distance, potentially long duration scenario that is not necessarily a military one.