A melee weapon against a semi-auto 5.56 broomstick
Wrong. Not against anything, because Kyle was literally trying to flee when he was struck.
But both are lethal weapons, so it’s absolutely reasonable and justifiable to use either of them to prevent being killed by someone attacking you with the other.
Rittenhouse was 100% in the right to shoot that guy, who was trying to kill him, and had already landed blow that could have succeeded in doing so.