"Judge Will Issue Subpoenas for Trayvon Martin's School Records and Social Media Accounts."

Jeralyn Merritt says this is "the correct ruling":

A defendant raising self-defense may introduce evidence regarding a victim's reputation for a particular character trait like violence to show that the defendant was not the initial aggressor, even if the defendant did not previously know about the victim's reputation. Here's the Munoz case the Judge cites from, which quotes the Dwyer case....

The judge is not saying the records are relevant or admissible at trial. Her ruling is in response to a discovery request, and the issue is whether the records could lead to relevant and admissible evidence.

From the Christian Science Monitor article on the ruling:

On Friday, Martin’s parents, Tracy Martin and Sybrina Fulton, called Judge Nelson’s decision to allow the school and social media subpoenas a travesty, suggesting that by opening up Martin’s records it would allow defense attorneys to “make a dead child seem as if they’re the perpetrator.”

In other words, the defendant is allowed to defend himself. Obviously, his only defense is that the "dead child" was the perpetrator. But the parents aren't legal experts (as Merritt is) and what do you expect them to say?