"If it was a threat, they should have gone to them as they were praying, waited for them to finish then ask them then and there what they were doing rather than haul them out of their seats long after they had left the vented area."
Could it be that it took some time to get the information to the people who make the decisions, and then some more time for them to review video of that area so they just didn't go detain these folks on someone's word alone?
A ducks in a row thing?
And let them spread Anthrax throughout the air ventilation system while getting permission from higher ups?
If you're going to run a police state, you need to be able to act faster than that.