It doesn't look good for the bank that employs the security guard. From other information in the article it seems the bank is improperly claiming the skyway as its own. They wouldn't even allow photography there.
Given the circumstances I believe the police had grounds to make a temporary detention.
agree with your first point, not so sure on the second. the police should know the scoop inre: private versus public areas and marked vs,. unmarked spaces.
the bank sure seems to be in deep doo-doo. IF we’re being given all the info