A 13 year old kid, honoring his family members who are veterans. I think this was obvious that it was pretty darn benign.
If the American flag has already taken on another meaning in the area, it doesn't matter what the individual's intention was.
A white Southerner could honestly perceive the Confederate flag as nothing more than a benign expression of cultural heritage, but if he goes through a predominantly black neighbourhood, it matters jack what he personally intends. A person would be doing him a favor by telling him to put the flag away.