Is it a waste, I don't think so. Museums are established to preserve history in one way or another so incarceratating a Spitfire will preserve that history. The aircraft was once a wreck and has been restored to flying condition but it is ageing and will come up with the standard Spitfire problems of old age. There are enough Spitfires flying around the world, mostly with remanufactured wings and the cockpit filled with gizmos so that it can fly in todays ATC envirionment.
It will probably still be there in fifty years time, the only drawback is that the Spitfire has no history in China so it will not be appreciated as much by visitors as in the UK but they have odd Russian, French and German aircraft in British museums so why worry.
The museum at Cosford has stacks of unusual aircraft that were built for research in the fifties but nobody is screaming for them to get airborne.