Its not an order.....it was a suggestion.
Zimmerman has the right to see where martin went.
It was an implied request by a representative of a law enforcement agency, therefore it had the weight of that agency behind it. Just as if your boss had told you the same thing and you did it anyway, you could be terminated for your actions... because the request or order was implied in the original statement.
Sure, Zimmerman had the right to stalk Martin if he felt like it, but he took his safety into his own hands by doing so. If you had someone following you around in the dark, wouldn't you feel threatened and possibly confront that person and ask them why they were following them?
I love how you're absolving Zimmerman of all guilt and placing 100% of the blame for what happened on Martin.