Evacuation through the terminal is surely only one limited option.
These people are not a threat to others or they would not have made it through security onto their planes. They require no further security clearance. They can be reunited with bags another day.
Evacuation by buses via other routes e.g. via perimeter emergency access points must surely make sense by now.
If there is any doubt, they can be profiled by the army or some such on their way out.