To put it in perspective, the goal is to combine a viable space suit and prosthetics to reduce the need for a fully biological human to participate in space exploration missions.
Thus, the bombs at the end of the Boston Marathon are part of the greater mission.
Putting the blame on some person or persons is a secondary function required to give Earthlings a feeling of justice served.
Anything else — fertilizer factory fires, earthquakes, etc — is a diversion to feed the various subpopulations their needs and wants — emotional attachment, hero worship, and so on.
treetrunkdings 