It is a federal crime to jam communications. I don't know all the specifics, but a Faraday cage built into the walls and ceiling of the building is legal, but any technology to jam a signal is illegal. (Unless one has to walk 25 feet away to get a signal not blocked by the size of the building itself.) If this company is broadcasting a jamming signal, they could be in very big legal trouble. I would love to know more about this.

This is the same problem the prisons are having right now. Cell phones are being smuggled in and the prisons want to jam the signals, but aren't allowed to by law. They could drape a giant Faraday netting over the entire prison, but it would be costly, difficult, and would probably violate some rule against blocking access to sunlight and fresh air.