Was Shooter’s Force Likely to Be Found Unlawful?
What the Sheriff had to evaluate, then, was whether the available evidence was likely to support a finding of self-defense, in which case the use-of-force was likely lawful and an arrest impermissible, or whether the available evidence was likely to fail to support a finding of self-defense, in which case the use-of-force was unlawful and an arrest was appropriate.

COTW: Florida “handicap parking spot shooting” analysis
Understanding Why No Arrest in Florida Handicap Space Shooting

Andrew Branca makes a point by point explanation why Sheriff Gualtieri did not present charges in this case. It is a somewhat long read, but do please take the time to read it. Also remember this is adjusted to Florida law and may or may not apply to other states, which is why you should be smart and get Andrew’s book and see where you stand.