So if Zimmerman was justified in attacking Martin because he felt threatened, wouldn’t Martin be justified in attacking Zimmerman because HE felt threatned? Woudln’t you feel threatned if a strange man was following you?
I thought we had well established that we don’t know what happened, so no opinion can possibly be correct.
In any event, the answer to your question is that luckily, the law has an objective standard, so that it needs to be that a reasonable observer would think you were justified in feeling threatened.