Excellent article and analysis - the case is pretty open and shut, the morality of American laws around self-defence and gun ownership is a bit more complicated. That's why the rest of the world is baffled - we have far tighter gun control legislation. In the UK, he would've gone to jail for manslaughter.
Under English law, according to R v Creamer, a person is guilty of involuntary manslaughter when he or she intends an unlawful act that is likely to do harm to the person, and death results which was neither foreseen nor intended.
The bit there is the 'unlawful act' - which in the UK and in most of the commonwealth, would've been covered by rocking up into a riot with a loaded gun of any kind, regardless of your intention. The Rittenhouse case is a distraction from what is really a debate on gun-ownership and is polarised along those lines.
You yanks and your armed bears!