Finding proof that Saddam's regime was training Palestinians is not that much of a surprise - there is a larger amout of evidence that the regime was backing the Palestinians
Therefore not much of a smoking gun. A Smoking gun would be proof that as the US claimed there is a connection to al-Qaida or bin Laden, which there is still no proof of. Or the discovery of WMD's in a quanity that posed a threat to other countries again the US was making claims of 100's of tons of chemical agent, or at least proof of an advanced WMDs weapons program.