My expectation is just recognition that some people may in fact question, disagree with or be skeptical of the prevailing viewpoint of a particular facet of this story and that that isn't necessarily motivated by secret racism, a desire, conscious or otherwise, to downplay tragedy or a need to be contrarian. Maybe he perceives the use of child or an emphasis on his innocence as needless emotional ploys. I don't know that I agree, but I can sympathize with that in a way, since his age and criminal history have no bearing on whether or not this killing was justified. That's maybe even a discussion worth having, but it won't be brought up if we just attack our own assumptions.
To me, this practice of focusing on motivations without any attempt to understand first breeds an attitude whereby anyone going even slightly against the grain finds themselves the target of barely veiled accusations regarding racism, pro-police defense force and so on and so forth. I don't think it's in the best interest of civil discussions of emotional topics.