You are completely ignoring Wisconsin Statute 939.48 (2)(a). His mere presence and having possession of a rifle is not sufficient to permit another person to attack even if he was found guilty of unlawful possession. Furthermore, the statute reads deadly force or threat of deadly force as sufficient grounds for self-defense. A person trying to take your firearm can reasonably be assumed to pose a threat of deadly force, especially if mere moments before that individual was saying they wanted to kill you and then attempt to disarm you. At any rate, this is a question of fact and, therefore, up to the jury to decide. The prosecution did not present sufficient evidence to meet their burden.

Section 948.60 (c) limits the application of the entire statute to Kyle. It states that the entire section (meaning all of 948.60) only applies to a person under 18 (which kyle was) IF they are in violation of 942.28 (which kyle was obviously not) OR not in compliance with 29.304 (this specific section only applies to minors that are 16 years or under, which Kyle was 17 at the time) or 29.593 (which deals with certification for hunting approval, which this situation had nothing to do with). Even if Kyle was in violation of this section, he would still not have surrendered his right to use Self-Defense.