After reading the text of the SYG law that I quoted, how can you conclude that the choice comes down to "leave or kill"? If you "reasonably believe you are in danger of serious bodily harm or death" then you have every right to meet force with force. Virtually everyone, except for predatory criminals will do their utmost to avoid killing another person, or for that matter even injuring another person.
If you are confronted by a guy, such as El Tiberon, sporting a big race boner who wants to ensure that you spend a few decades in a coma atoning for your whiteness, you have every right to meet force with force. If you are confronted by one of Buck's stormfront buddies who wants to beat you into a pulp to see if black people bleed like everybody else, you have every right to meet force with force. It's that simple.
SYG laws shield you from bogus prosecution and intimidation by the courts when you act to defend your life. SYG laws are awesome. Those laws put predatory criminals in a tough situation.
Here are some tips for you tough guys that like to "throw hands". Don't assault people. Be polite and respectful to others. Treat others the way you want to be treated. If you don't follow these very simple rules, expect to meet somebody tougher, or better prepared than you.