Wrong again, but thanks for making a false assumption on behalf of the "Chinese boys" here.
Anything which causes instability in the region threatens China's interests, and threatens the status quo.
A Korean war would damage the regional economy, as well as sending hundreds of thousands (or even millions) of North Korean refugees streaming over the Chinese border.
Any way you look at it, a war in the Korean peninsula is bad news for China.
Any provocation that increases the chances of war, is a bad thing to me, regardless of which side makes the provocation. And before you make another assumption, I consider the lethal shelling of Yeonpyeong island, to be a provocative act by the North.