This despicable tyrant is making WMD for offensive purposes. There is no defensive purpose for making bio-weapons.
Not to defend Saddam, but actually there is such a defensive purpose. It's to serve as a deterrent against others' using those weapons against you. That's why we developed them ourselves until Nixon's presidency.
What worries me about this scenario is I've heard Saddam's two sons are worse than he is, and have already made threatening statements if anything happens to "dad". And undoubtedly there is a whole army of this ilk waiting in the wings to take over should something happen to the sons. We'll have to exterminate the whole bunch - that might not be easy.
This may be why the Bush Administation is hesitant to link Saddam to the attacks...they may just be buying time to figure out a strategy. And given the obvious ramifications, I think they want to be as certain as possible of Saddam's connections.