Although the younger generation in South Korea doesn’t have the hunger for reunification of their parents and grandparents, very few are hostile to the prospect per se, they are only concerned about the cost.  It seems unlikely that this would in any way reflect the ‘50-53 war which was a battle between the US, the Soviet Union and China and just happened to be hosted on the peninsula and to its huge cost.  One of the advantages of involving China is that it would be the clearest possible demonstration to the South Korean people that the superpower was committed to the long process of rebuilding their mutual neighbour.  This answers several of the possible objections. China gets the benefits of security and South Korea gets an important ally in the process of rebuilding the North.