He may. Or he might not. I'd make it a 50/50 proposition.
I can think of two reasons not to. The first being that while we might be certain the anthrax came from Iraq, we can't necessarily prove it, in a legalistic fashion. The circumstantial evidence might be overwhelming, but the employment of "plausible deniability" might preclude an ironclad link. Or there might be intelligence sources that they don't want to compromise.
Perhaps an announcement might be forthcoming after the war is over and we can examine his laboratories and biowarfare personnel.
The other reason might be even more compelling. If some other tinpot despot discovered that, after discovering an Iraqi connection to 9-11, we remained quiescent for over a full year, he might conclude that "blackmail by WMD" could actually be made to work. We would definitely want to dissuade him of such a notion...