The question the defence asked of Botha was - could the witness hearing these arguments be 100% sure they came from OPs house from that distance. It's a rhetorical question really because of course the answer would be no.
In the trial the jury will apply their own interpretation as to what is a reasonable likelihood. Not sure why its a major debating point. It was a predictable question that any defence barrister would pose of a witness in such circumstances.