I'll rephrase: "I don't necessarily believe in 9/11 being a conspiracy by the US government"
I respect that but also gently point out that members of the US government have stated they were stonewalled in their investigations by other members of the government, specifically the Executive Branch and intelligence sectors.
Efforts to cover for one's own negligence in the commission of a crime that one had no part in puts someone on the same moral and perhaps legal ground as the actual criminals.