He may not know the 911 call was recorded...however, he knew there were MANY eye witnesses that heard those screams. He had to explain where they would have come from - whether they were Trayvon or himself.
There is in fact evidence he continued to follow him. He said "OK" to the "we don't need you to do that" 20 seconds after he left his car.
However, he stayed on the for for another 90 seconds. If he had not followed him, he would have already been back in the safety of his car for over a minute.
We know, if my timeline is correct, over 2 minutes later, Trayvon was shot.
And GZ was NO WHERE NEAR his car!!!
So where was he all that time? If my math adds up and my timeline is correct, that's over 3 minutes.
Except as pointed out, 20 seconds after he left his car he told the 911 operator "OK" to not following.
Clearly, he didn't follow 911 instructions. Clearly, the evidence shows he was still following.
And of course, this witness stated TM told her a creepy blah blah was following him.