It won't.
then his death might do some good.
The "good" that came from Martin's death is the fact that he (Martin) will never be able to harm another human being, black or white. A non quantifiable number of people may well live to be of an old age because Martin is no longer on earth.
How many lives did Zimmerman save?
There is fairly large segment (approx. 1/5 to 1/4) of black males who grow up almost completely uneducated, feral, and violent with great hatred towards white people or anyone perceived as easy pickings. They are the most dangerous and worthless American citizens...(arguable since white liberals/leftists are almost as big a threat.) If word spread, as it would, that assaulting innocent people might lead to getting your head blown off, hopefully the black terror inflicted on innocent white AND!!! black people by feral, black youths will be halted or at least deterred.