This isn't true. You can't intentionally use paint or wallpaper that blocks signals in public spaces or places where a wireless device is expected to be able to be used(like a movie theatre) in the case of an emergency.
In the eyes of the FCC it is no different if it is willful.
There is indeed a distinction between your own private property and a business that invites the general public in to do business. The cinema is still private property, but it's still also public space.
That said, I don't think anyone has ever attempted a ruling on whether chicken wire/Faraday cage in the walls of public spaces is permissible according to the FCC. I'd doubt such an attempt would make it far; there are so many buildings made with metal siding which do a fantastic job of reducing cellular signals to useless levels.
In the eyes of the FCC it is no different if it is willful.