Maybe I'm just a callous person (without kids), but I would not have waited even 5 minutes if they pulled this on me, and would have called the police to report false imprisonment if they insisted. What good is keeping me there? Am I going to walk out of there with a kid in my pocket?

The GM should contact his corporate lawyer if he thinks that's a valid policy. Even suspects in a questioning room have to be either arrested or released at some point.