Irrelevant. Xi wanted to make a point but not only that, he wanted to make that point irrevocably -- that I am in charge.
Can Hu Jintao be instructed not to show at the congress? Yes, I could have so instructed or even prevented by force, but I want everyone in China and in the world to know that I am in charge. I want his removal from China's political life to be as public as possible and to be politely but firmly done to show all Chinese, party member or not, that my will cannot be challenged no matter how restrained I may seem.