I think it was a Newspaper story of an interview with NOPD about Guns in the French Quarter. I was skeptical about IR cameras with that kind of resolution. Probably propaganda.I have never heard of thermal cameras being used to identify firearms in any city.
Last time I went to the WWII Museum (years ago) there were no firearms signs on the doors. It's not technically a firearms free zone as defined in the law. Do what you need to do. Concealed means concealed.
Edit to add that the museum admission is half price for LA residents for the month of July.