You say IAEA seal and inspection as if it means something. Who inspected the thousands of tons of yellowcake left under Saddam’s control when the inspectors were expelled from the country for five years?
The whole point is this particular yellowcake, and the previous 2 tons or so of low-enriched uranium, are not any sort of in-your-face discovery. They’re remnants of the pre-1991 program, that were well known, and were not a particular issue for the UN or the United States. Any other aspects of the Iraqi post-1991 program are a separate issue.