Absolutely not. It may make it impossible for one side or the other to meet a burden of proof, but it certainly does not make it "true".
I absolutely agree that it will be tough to disprove beyond a reasonable doubt Z's self-defense claim. Proving a negative, especially to that burden is very difficult; especially when all adverse witnesses to the start of the fight appear to be dead.
That however in no way means that it is true or proven that he acted in self-defense. It just means the state couldn't meet an extremely high legal burden of disproving it.
What is true and what can be proven beyond a reasonable doubt are not the same thing.
Joe
Joe, c'mon, direct admissible testimony versus unsupported speculation? Just because the truth is beneficial to the defendant does not make it "self-serving." If there is any quality evidence, direct or circumstantial, that shows Zimmerman either threatened, laid a finger on, or otherwise attacked Martin, I'd lead the cheer for the prosecution, but they've got absolutely nothing (so far) that contradicts Zimmerman's version of events, and he has partial corroborating testimony. (Strong caveat here: that we know of, there may be other unreleased or as yet undiscovered evidence blowing up Zimmerman's story). I'd like to hear testimony from a disinterested third party on how the final altercation came about, but it just might not be out there.