I don't see any evidence at all that Sadaam was conveying an impression that he had WMD. The Iraqis consistently for years said they didn't have any, because they destroyed them all. That turns out to have likely been the truth. No obfuscation there. As to why they impeded some of the inspectors the reason they gave is they believed some were spies (true and admitted by the US later) and because they wanted to protect the presidential palaces. Now it has been conclusively shown since that there were no secret bunkers of WMD at all under the presidential palaces, so the Iraqis were telling the truth there as well.
This line about the Iraqis "pretending" they had WMD by vigorously deying it seems to be the last fig leaf still to be torn away about the whole matter. It turns out that all this suspicion was paranoia. They said they didn't have them, and they didn't. All the reasons they gave for not full cooperation with the inspectors turned out to be true. You get left with this ridiculous argument is the reason they were denying having WMD is becaise they wanted us to think they really had them. By this argument there was no way they could say anything at all without it being added to more evidence they had them.
If there was any additional reason for non cooperation it was the lack of a carrot to balance against the stick. They were under the impression that cooperation would not lead to the sanctions being lifted so noncooperation could be held back as a bargaining chip for sanctions being lifted. It didn't work because the policy at the time was to never lift the sanctions till Sadaam was gone.