Then some of them will really fight with the lock refusing to leave.
Mitigating against that exact misunderstanding was part of my suggestion - otherwise you could just lock them with no lights/explanation, but then you'd run into the problem you describe.
Edit: I'll add that I was in a retail store (employee) that was evacuated by police, due to an armed gunman. People were still worried about the office chair or shredder that they wanted to buy. An officer had to basically get up on a counter, and hold up his gun and badge and say, "Everyone out! Now!"
On the way out some guy was trying to ask me if we would be open later because he (apparently) really wanted to get this office chair he was looking at.
It's human nature. You have to work with it, not against it.
The people who brought their bags off the plane today have their clothes, laptops and passports tonight; they can go to work tomorrow. The people who didn't are locked up in a customs holding cell, wearing the same underwear, for a few days until someone can issue them a passport. They'll never get their bag back and the airline will, after filing dozens of forms, compensate them about $50 for it.