Surely it's overly reductive to imply -- as he does -- that it's simply the number of deaths, or even the number of deaths and serious injuries combined that should drive our response to these events. The social significance of a truly terrorist act directed at one of the biggest annual events in the Boston area warrants some degree of extraordinary effort, not to mention the public danger of literal bomb-throwers on the loose.
Not to mention inconsistent with his own reactions. I don't think rms spent all day today mourning the Holocaust or the fallen soldiers of the Civil War.