Yeah, I heard about that, but I don't know where the terrorism thing figures into it. As far as I can tell the major reason was Daley's domineering ego and desire to run Chicago like a third-world dictatorship. I can tell you that terrorism factored into no part of the decision other than the PR spin.
Planes were sitting at the airport, unable to take off because he ordered the runway to be bulldozed in the middle of the night.