I keep going back to this post:
http://en.wikipedia.org/wiki/Monday%2C_Tuesday%2C_Wednesday%2C_Thursday%2C_Friday%2C_Saturday%2C_Sunday#Err
"Err (voiced by Matt Maiellaro) is second in command of the Mooninite Army (although he and Ignignokt are the only members of it). He is purple and smaller than Ignignokt. He is known for his trash talk, and he is usually the one who coerces Meatwad into going along with Ignignokt's schemes. In his most recent appearance, he claimed that the Mooninites only act the way they do due to a need for attention. He is a terrorist in Boston. Err fits precisely into the notch on Ignignokt's head, and when combined they can pool their firepower into the "Quad Laser", which is a stronger, yet slower, version of their standard lasers. A larger and more powerful version of this attack, the "Quad Glacier", which is done by replicating themselves into the form of a massive pistol, moves at a pace that barely registers to the naked eye. On January 31, 2007, a number of "devices" were found in the massachussetts area with the classic image of Err "shootin' the bird." These devices were essentially found to be a hoax.:
..."HE IS A TERRORIST IN BOSTON..."
I am sorry folks..these 'fuffernutters' need to be strung up!
If these are the primary characters, then you have identified the answer to why Boston was the target city.
In an earlier comment, you expressed doubt whether other cities were included in the device planting as was claimed in the report. You're probably correct.
Fox just reporting a second arrest. Said the men were hired by Turner Broadcasting. Reports are mixed whether Turner or the advertising group initiated and executed this stunt.