People keep using the UN as an excuse for the US attack on Iraq (as beardedbruce did in this thread, and Teribus has done in other threads) and only fall back on "the president didn't need UN approval in order to attack" line after the UN line of argument has been thoroughly debunked, as we can see in this thread and numerous other threads. I wonder why this is.

If the argument that the president didn't need UN approval is so solid, why do people like Teribus and beardedbruce only use it as their fall-back argument?