Why didn't President Obama raise the issue of the Iranian uranium facility at the UN?

My theory is that he didn't want to demonstrate the farce that the UN is, anymore than he had to.

By bringing it up at the G-20, he avoided a tea party outcome in the UN session, and having to make any decisive moves. Instead, he can lob the ball back while the delegates are traveling back east.

I suspect a pattern of avoidance coming, with a veneer of strong words. I hope I am wrong, and this is not the latest paper tiger.