What you said doesn't contradict what I said. What you're actually asking is that Manning provide the evidence that Levin *should have had* when he was running off his mouth. This is punishing Manning for trying to defend himself through the only legal means available to him.
I say - if you're running off your mouth about lies for which you have no evidence then you're just as guilty of libel whether or not what you say is true. Or at least should be discouraged. Otherwise that gives me the ability to go running around slandering others as a way of forcing disclosure of whatever I want (transactions, proprietary data, sex tapes, etc.).