It says we could never verify so that means not proven it is obvious he did though.
You said Saddam Hussein did not plan or participate in the attack on the World Trade Centre. You seem 100% sure he had nothing to do with it.
There is no evidence to support the view that Saddam Husein had anythng to do with 9/11, none.
Given his non existent relationship with Al Qaeda or any Islamist group, it is highly unlikely that he would have entertained any such cooperation. In fact the US Senate and the CIA both put forward evidence that the Hussein Regime had rejected several attempts by Al Qaeda to formalise any kind of relationship prior to the 2003 invasion.
In 2005, the US Senate Intelligence Committee concluded that there was no formal links between Saddam Hussein and Al Qaeda and that the regime played no part in any Al Qaeda operations prior to the 2003 invasion.
It said that the Iraqi Regime and Al Qaeda were ideologically poles apart, and that the Iraqi Government did not have a reltionship with, harbour or turn a blind eye towards Zarqawi or his associates.
It stated that Saddam Hussein was distrustful of al-Qaeda and viewed Islamic extremists as a threat to his regime, refusing all requests from al-Qaeda to provide material or operational support, the Iraqi regime had repeatedly rejected al-Qaeda requests for meetings.
The report from the committee also reffered to the role played by inaccurate information supplied by Iraqi opposition groups in the run-up to the war.
So no, it is not obvious that he did, quite the opposite in fact. It is obvious that he did not.