Depends how you define “aggressor.”
They are defining it as Z following M down the street and then the sidewalk. That if he had just driven on past none of this would have happened. Which is indisputably true.
I think a reasonable person defines “aggression” as something more than following someone or even approaching and questioning them.
But he didn’t follow him. He watched him, but he didn’t follow him. There is not a shred of evidence that he did. He calls 911 says there is this guy looking in houses, he drives past Martin and parks his car. Martin walks towards Zimmermans parked car with his hand in his waist which GZ describes to the 911 operator. Trayvon then circles Zimmermans car. To me that was to check if Zimmerman was alone. He then walks away and disappears. Zimmerman gets out of his car TO follow him, starts running in fact, but he lost him. You can’t follow somebody if you don’t know where they are. 911 guy says don’t follow him so he stops running which you again hear on the 911 tape. 911 guy then asks ZImmerman what street he is on, Zimmerman says I do not know. So he goes to check the street sign and that is when Trayvon atacks him.