It depends on the properties of the cage. In terms of blocking harmful EMF, it is certainly a boon to health. My body has recovered significantly from earlier microwave targeting thanks to the Faraday tent I use; this very tent from Holland is marketed to embassies for this same purpose, as US diplomats are targeted with EMF abroad. So the governments likely see Faraday as a solution and have done more research than you and I have. To say Faraday will or won’t work as far as improved health is a bit glib; it depends on the implementation and usage.