I'll bet there still would have been a lot of complaints here, unless a link between Iraq and 9/11 had been clearly established.
A lot of people complained about Serbia, but nary a peep was uttered over Iraq. Had he invaded Iraq, many here would not have questioned it so completely. The CRS reports for over 9 years had warned us about Saddam's threat, and since the ChiCom/Iraq connection was established through Project Chinagate research, some wouldn't doubt they got their hands in the WMD cookie jar again.