Why?
I don’t know why the cops muted their camera audio. I was watching the police-released video on Fox last night, and it included the part about one cop telling the other one to turn off the audio. The report included video segments from the aerial (in thermal imagining) and the cop’s body cams. Turning off the body cam audio was very briefly discussed by the cops...and deliberate. Reason unknown.
An interesting aside... In the aerial thermal imaging, you could see the perp on the ground, presumably already shot and down, with the cops continuing to fire. You could actually see the spark of the bullets ricocheting off the concrete patio near his body.