I think the point was a reaction to the word “child” as pandering to a false image of Michael Brown as some sort of frail innocent.
At over 6ft and over 200#, even if you’re not 18 yet, you’re certainly a more physically imposing figure than many adult males will ever be.
That being said, regardless of size or age, nobody should be subject to injustice by those who are tasked to preserve it. It’s too bad that all the information seems to come from one of two camps, the “my innocent little baby” camp or the “drugged up giant potential cop-killer” camp. Each side is so blatantly pandering to cultural tropes, and trying their damndest to manipulate facts to fit their agenda.