Some of the codes that mention establishments where alcohol is served by the drink. For example, Des Moines Muni Code: (1) Except as provided in subsection (2) of this section, it is unlawful for a person, on or in a premises in the city where alcoholic beverages are dispensed by the drink to: (a) Carry a firearm, rifle or handgun, whether the person has a license or permit to carry a firearm or not, and whether the firearm is concealed or not; Subsection 2 is the standard law enforcement official duty language. My interpretation of this is that the entire restaurant (such as Red Robin) would be off limits, even in the dining room.
You are correct that this code does violate state law. It is greatly more restrictive than what the state has to say. You would be in violation anywhere in Red Robin, not just that portion that is restricted to those under 21.
As for suspending rights in an emergency... Unless there is a right in State Law allowing suspension of firearm rights, then that too would be more restrictive.
