No time to pull a direct quote, but, many of us have posted references to the TSA clearly stating that they aren't responsible for "security" outside airside. They have even gone on record stating that they aren't responsible for securing the airport perimeter -- usually when some clown drives onto the tarmac and starts checking out some of the flight hardware. I also believe they said they weren't responsible for securing the landside check-in line when a guy shot a bunch of people at the TBIT at LAX a few years ago.

The only thing the TSA says they are responsible for is checkpoint and checked baggage drug busts.