Honestly it seems kind of a far-flung premise. G. W. Bush and Colin Powell grossly overestimated Iraq's nuclear (And other WMD) programs on almost no real evidence because it was what they wanted to believe, a lot like LBJ and the Gulf of Tonkin incident. Unlike Afghanistan under the Taliban, he didn't have and never did develop anything publicly-released that showed Saddam had Jack to do with al-Q'aeda, who were as big a threat to the secular Ba'athists as they were to the West, if not more.
It was either incredibly poor decision-making based on wishful thinking and unicorn magic, or a fiendishly-clever manipulation of the situation to take down an implacable long-term foe when the opportunity presented, even though Saddam wasn't actually a current threat to us at the time. I'm not sure which.
The problem with relying on hyper-classified intel for such decisions is that there really isn't anyone to do a reality check on it, because everyone who actually has enough access to it to have a meaningful opinion has already bought a ticket on the Administration's crazy train, since the three biggest votes on it are all Presidential appointees - SecState, SecDef, and National Security Advisor. The CIA itself has a pretty long history of telling the President what the SecState thinks he wants to hear by the time the intel gets to the top of the food chain, no matter what the actual intelligence analysts think of it.
