Seems to me that the disclosure of Iraq chemical weapons having connections to the US as an enabler would be an embarrassment. Since the post WW1 days, the US has been a leading proponent of banning chemical weapons on the battlefield and especially against civilian populations. I could see the need of silence being necessary to not expose to the world how once again Washington speaks with forked tongue!
THE USA signed an agreement in 1975 to ban chemical weapons use, and IRAQ did not. The USA provided the chemical weapons that IRAQ used in violation of this agreement.
The CIA knew this, and did all they could to shield the USA from exposure. When we invaded, we had even bigger reasons to hide the origination of these weapons. BUSH's father helped to provide them.
TOS.