How could they have used them on the Kurds if they didn't have them? IIRC didn't the inspectors or somebody find the artillery shells for binary agents? Any decent chemical plant can handle the production.

Edit: The Iraqis knew where the inspectors were going well ahead of time and many places were off limits between Desert Storm and the Iraq War. This is the same problem that the Iran nuclear deal had. The Iranians could delay or prevent the inspectors from looking at particular sites and the appeal process would take significant time.