If true, seems to be a bit sporadic. I have a feeling that witness credibility , perceived or actual, played a large roll in the decision.
You do realize that witness interviews and GJ testimony are 2 different things? No, guess you don't. Your thread title is a lie. Most of the so-called witnesses changed their stories when in front of the GJ.
The witnesses admitted they lied in the initial interviews and revised their stories, more in line with Officer Wilson's account. Those interviews were part of the evidence seen by the GJ to make their just decision.