Why did they need to convince Henderson of this? All Superman needed to do was arrive alive. At this point it is crystal clear that Clark did not kill Superman. Henderson already had his doubts about Clark killing anyone.
Well,it might be crystal clear that Clark didn't kill the real Superman. But in my humble opinion he needs to prove that he didn't kill the clone either. Cloned or not - the fake Superman was a a human being and killling him is a crime, even if his life wouldn't have lasted more than a couple of weeks anyway.
Now you could argue that Clark couldn't have killed anyone with a kryptonite bullet. But how would Henderson know that, assuming that - officially - kryptonite does not exist.
