Paging Justin Trudeau.
Call your office.
The main point? Tzarnaev (allegedly) put a bomb next to a child. When you approach that degree of unqualified evil, the "why" doesn't matter quite so much any more. You can't use the "root causes" ruse to try to pin that one on society. As John Robson notes in The Sun, quite correctly I believe, "the question of root causes would be interesting if the phrase were not clearly code for 'it's our fault.'"
My personal favourite line from Gutfeld's Twitter rant (if only because I actually watched Wolf Blitzer doing this yesterday):