That won't work. There is no evidence that Iraq was involved in the WTC and Pentagon attacks, and the congressional authorization was only to go after those responsible for these two attacks.
Like it or not, their are some in the middle east who have declared war against us. Saddam may or may not have had direct hand in WTC, but he is providing financing for terrorist groups.
Not doing anything (other than warning him) will not stop terrorism against this country. Taking out the source of finacial aid, and base for operations will.