Criminals are generally dumb. These guys apparently didn't plan very well for what would happen if anyone figured out it was them. Seemingly the plan was to go back to their regular lives until they dropped off another round of devastation, perhaps along the Esplenade during July 4th.
"I love signature blocks on the Internet. I get to put whatever the hell I want in quotes, pick a pretend author, and bang, it's like he really said it." George Washington