Kyle responded to the needs of the people who were being left to defend themselves, and that's exactly what he did. He is not some "dumb kid". He is a young man with courage and honor in his heart, who had not had much experience in fighting mob forces, yet conducted himself in the most exemplary way. He did not shoot at anyone who was not a threat, and he immediately attempted to turn himself in.
Someone tried to portray KR as a kid with a “hero complex” that wanted to save the country. Someone else pointed out that is precisely what makes up the US military.