The security guards were brutal at Intel in the 80's. You had to sign a waiver that gave Intel permission to keep anything you were carrying on your way out. They did it too (confiscate things they felt shouldn't leave the building). Most people were smart and just left everything at the desk.

That said, these days with phones and laptops being nearly attached to the wrists of folks it would be a very hard policy to enforce. Google's solution was conference rooms that were outside the security perimeter and had bathrooms outside the security perimeter as well. That worked pretty well and would have defeated this particular attack.