With that said, i want to point China is Chaotic neutral. Meaning its self interested, the 5 in security council are all self interested. This implies that what stability means for US, or UK wouldn't necessary apply for China. IF something horrible in Africa, China wouldn't oppose sending UN forces. That may put an independent/ different perspective. For example: IRAQ, it is better? For some yes of other no. China abstention in IRAQ war UN vote.
#2 what UN partly do. For the most part clean up or prevention of events from being bad to horrible. Thus "stability". Another function is the prevention of the world most powerful nations going to war with each other.
Yes, China is a stabilizing force in the United Nations, because it is so economically powerful. China sells many billions of dollars in goods to the United States each year. They are unlikely to want to destroy a country that they earn lots of money from. China wants to continue to profit from their efforts, and will encourage stability.
China is in a position in which they control much of the world's manufacturing, and as such, have an unequal position compared to much of the rest of the world. Until China is subjected to similar labor laws to that of the US or is forced into a lesser position of power, they shouldn't be seen as a force for "good".