1. He did not illegally own the gun.

2. His only rule violation was breaking curfew, which pretty much everyone out on the street was.

3. Unless you can point to the law, merely being on the street with a legally possessed firearm does not, in any way, waive your right to self-defense.

4. There is actually a lot of evidence that shows that kyle was administering first aid and helping put out at least one fire that night, so the statement that he was just out there to cause trouble is also pure speculation.

We live in a country with laws and if you violate that law, the prosecution (not the defense) has the burden of proving their case. That standard is "beyond a reasonable doubt" which is the highest standard in the american legal system. You can speculate all you want and, in the court of public opinion, he may have been judged guilty. However, under the American legal system, he was acquitted and if we are to remain a society that should promote justice, then we have to respect the verdict.