This page disagrees with your account of the story:
link
I don't knwo enough about this case to separate fact from fiction, but it appears that there is much more gray area to this than you are giving it credit for. If it were so obvious that this guy was acting in reasonable self-defense, why would he have been convicted? Yeah, juries are dumb sometimes, but I'm not ready to jump to the conclusion that this guy is compeltely innocent.