While they were investigating the building, Dustin sent them a message: FBI and Homeland Security are here. I'm in their car.
Luke wasn't too surprised.
The explosion on Wall Street earlier had been in too sensitive a location.
Also, it proved that Simon's "game" wasn't just for show. There were indeed follow-up arrangements that could be triggered at any time.
The FBI and Homeland Security couldn't sit still anymore.
If this continued, even if they didn't have to take full responsibility, the person in charge still wouldn't be able to bear the consequences.
It didn't matter what the higher-ups thought, but the people in charge of these two organizations in New York didn't have the courage to take the blame, and had finally come knocking.
Luke simply sent a message to Dustin to turn on the Internet call function on his phone so that he could listen in.