Although the above quoted doesn't seem to cover what seems to be the "vaguely threatened" situation I understand the Trayvon Martin case to be.
But legally following someone might reasonably create a situation where said followee objects and challenges you. You might reasonably and accurately, perceive a substantial chance of getting your butt totally kicked in such a situation. The law appears to allow shooting in this situation rather than backing off.
And as Dr. Adequate points out, if the teenager was legally armed, he would certainly have been justified in plugging Zimmerman. Is this really the way any sane person wants his neighborhood to work?
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison