That is conflating terms that don't mean what you think they mean.
Neither handcuffing, transporting, or taking of voluntary statements is in and of itself illegal.
Investigative detention absent probable cause is prohibited by the immunity statute.
A person who uses force as permitted...is justified in using such force and is immune from criminal prosecution and civil action for the use of such force... As used in this subsection, the term “criminal prosecution” includes arresting, detaining in custody, and charging or prosecuting the defendant.
The responding officers termed Zimmerman's transport to be "investigative detention."
I'm not conflating any terms and have read the statue many times - as have you. Are you claiming that investigative detention is allowed - presumably absent probable cause?
Reasonable people can disagree about meanings or interpretations. I am quite open to having my errors pointed out. Hell - I prefer it.
So, which term am I misunderstanding?