Premise: There is an invisible "only" in front of the words "Black Lives Matter"
Critique: There is a difference between focus and exclusion. If something matters, this does not imply that something else does. If I say "Law Students Matter," it does not imply that my colleagues, friends, and family do not. Here is something else that matters: context. The Black Lives Matter movement arose in a context of evidence that they don't. When people are receiving messages from the culture in which they live that their lives are less important than other lives, it is a cruel distortion of reality to scold them for not being inclusive enough.