It sounds like a perfect plan to me: have bad guy #1 run in through the out door, causing TSA to evacuate the terminal, and then have bad guy #2 kill a thousand or more people after TSA plays right into the plan by congregating the masses in one vulnerable little spot.
This is exactly a tactic developed by several external terrorist groups and other internal criminals. The most recent I remember was the people who were bombing abortion clinics here in the US.
It was simple -- they would use two bombs. The first one was a little one designed to evacuate the clinic and to draw attention. When everyone was congregated in a central, usually confined area, the second bomb -- the killer -- would detonate. This isn't rocket science.
"But, Mr. President, despite the fact that 500 people got killed outside Terminal 2 after we dumped the terminal, we made sure that missing pocket knife didn't make it on an airliner!"