Why Does New Orleans Mayor Ray Nagin Fear the CIA?

I think it is unlikely that he was simply worried about his criticism of Bush.

This aspect of the Katrina disaster should set-off alarm bells:

In an interview by WWL TV, Mayor Nagin complained vociferously that Louisiana National Guard Blackhawk helicopters were being stopped from dropping sandbags to plug the levee soon after it breached. There is evidence that no repairs were allowed on the levee until after New Orleans was totally flooded!

However, the media has been almost completely silent about this blatant stand-down order-- much as they have been silent about the air-force response on 9/11.

Much more likely than that Nagin was worried about criticizing Bush, it is that he knew what the plan was for New Orleans in the aftermath of Katrina: an illegal land-grab by "white folks".