And, since the moment when the two found themselves face to face was unrecorded and, as far as we know, unwitnessed, nobody can say with any certainty (speculation but not certainty) who initiated the confrontation.
You are missing the point. If Zimmerman had lost Martin it had to have been that Martin turned back (completely negating any possibility he felt threatened), and brought about the final face to face.
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I'm not missing anything.
Without any witness to the events nobody can say what happened...not even you.
It is entirely possible that Zimmerman continued to look for Martin and found him. One could argue that this is more likely since we know that Zimmerman was following and we know that Martin avoided a confrontation by running away.
Things are not so just because you or anybody wants them to be. Most people realize this by a certain age.