Controlling access and egress is a very basic security precaution. I work in a building with 1200 employees. How many entrances do we have? Two. Just two. Those are positively controlled with card readers, turnstiles, metal detectors and armed guards. We probably have a dozen exits, but the doors don’t have exterior handles and alarms ring when they are opened. Every employee and visitor is identified, if appropriate, they are searched. But if an emergency situation happens there are more than ample ways out of the building.
That is what Lieutenant Governor Patrick was talking about. This is not rocket science. This is a basic tenet of modern school construction (my daughter’s middle school has exactly one entrance). It is only mysterious to politically obsessed ninompoops.