This is a huge pain in the ass. When I travel, I often don't use my phone for many days at a time, and usually return without a charged device.
This new rule will get them a lot of public kickback if they continue to enforce it. Bottles of water or nailclippers are cheap and have no personal attachment. Phones are expensive and people's lives are wound around them - not to mention that especially in this digital age, I wouldn't be suprised if more than a few people travel with no itinerary beyond what's kept on their phones.