Apparently he was sitting in a skyway lounge area waiting for his kids, and the nearby security guard said the seats were reserved for building employees. The St. Paul Skyway itself is public property, but I don't know exactly where the seats were. Nevertheless, the area was not marked private or restricted. When the cops asked him to move, he complied. But when they then demanded ID, he refused.
A review board is now reviewing the case. The mayor is also calling for a full review.