I would not say it is a bad time per say. As a person that lives on the east coast and keeps up with it. I can tell you storms can get brewing then. And it can get really hot.
Carnival will re-route the ship to avoid any storms, and change the ports of call. But leaving from N.O. you are pretty much stuck with options in the Gulf, would be my only concern.
Have been re-routed from Western to Eastern leaving from FL late Oct. But they had that option. Personally, I only black out the 1st. week of Sept. thru the 3rd week of Oct.
I would still even cruise then if the price was right. Most of the time is no worries