It indeed is essentially a Faraday’s cage, unless the door is open. But you are right, mobile phones would be rendered useless while charging in the room. However, from the conclusion section of the original author’s paper:
“Finally, the high Q-factor and sub-wavelength operation of the QSCR room permits the inclusion of windows and doors, without significantly altering system performance. In the long term we believe the requirement of metalized walls, ceilings and floors can be significantly reduced by optimizing the QSCR, and retrofitting of existing structures will be possible via modular panels or conductive paint.”
Perhaps a later iteration may help address these points brought up in the discussion.