Or, to put it more realistically, because people might come to understand that we have been successfully blackmailed into letting Saddam off the hook for 9-11 by his subsequent threat to anthrax the US population.
The people will accept this, BTW, because nobody wants to die. We f***ed up big time (or rather, Bill Clinton f***ed up), and now we have to live with the consequences. But the atmospherics will have to be handled delicately. Hence the Amerithrax hijinks -- and the nonsensical stories about waiting on snapshots secretely taken by Czech emigres to decide whether or not Mohammed Atta did or did not meet Iraqi agent Ahmed Khalil Ibrahim Samir al-Ani. Like the replicants in Blade Runner, the public needs a "pillow" for its emotions, and Bush is providing one.
For Saddam to accept this kind of deal, we have to provide him guarantees that he can trust. What kind of deal could we make that he could be sure we couldn't back out of?