How do you know she was telling the truth?
There are cell records that Martin was on the phone with this girl, but she is clearly lying about what he said.
He really said, “hey, don hang up, I can’t talk cuz I’ma gon run round the block n hit this cracker good, but you stay on and say I wuz jus talkin wid you n he jump me.”
That’s what really happened in the Hydrazine scenario world. The girl is lying and Zimmerman is telling the truth. We know who was lying and who is telling the truth because... how do we know this?
We don't.
But the call log nails down the timeline, even if we have only her account of what he said and what she heard. If there's a trial, the jury will have to decide if she's believable, what to make of the timeline, and how it fits with other testimony.