It seems like LE solved this in spite of themselves and only because the perp decided to be as helpful as humanly possible. And even then, it doesn't sound like they have the strongest case in the world yet. "The interpretation of identification is subjective in nature" is not a phrase I want preceding the one test that ties my defendant to the crime scene. At least RA helpfully ruled out all the other explanations as to why a bullet of his would be there. But I hope they do a better job preparing their expert witnesses than they did investigating this case.
I suspect that is boiler plate text for the expert examination. It just says this type of analysis includes both objective and subjective elements.