I wonder if the cops had the legal authority to search him or demand his ID, or if he voluntarily gave it? I guess they somehow got his name if they're to do a background check.
The way I understand it (and not knowing Colorado's statutes) without probable cause or other legal grounds a person has no legal obligation to surrender ID to an officer. I have no idea if being a "weirdo", odd or goofy is enough, especially if he wasn't threatening in any way.