I won't answer the part about IOK or UN resolution since I consider it to be irrelevant. Now since you have accepted that Pakistani state isn't involved in this incident I would talk about the inactive part of your post. How did you realized the inaction of the Pakistani state. It is Pakistan among all the 50+ muslim states which has supported China on Xinjiang issue. It is Pakistan which extradite all the most wanted militants of ETIM back to China. As the member Chines Dragon said it is because of Pakistani state that China is low on terrorism risk index. Even the religious organizations like Jamat e Islami opposed any militant movement in Xinjiang. In short Pakistani state had done more action against ETIM than all the verbal bla bla of the Indians on this thread.
I don't see any inaction here.
Obviously no. Since it is some Chinese citizens who were involved in this incident and state of Pakistan is more than willing to quell any such group who is involved in such incidents. China knows how to make it safe and it knows bombing someone else territory is not the way to make itself safe.