So the goal is to allow a guy who made baseless claims to go hunting for a base?
No. The goal, as I said, is to allow the person being sued to defend himself. You want to take a public squabble to court and have a judge rule on it, you have to accept the side effects. You don't want those issues raised, let the character of the person making the statements you don't like speak for itself. Personally, I find it hard to believe that anyone in the climate science field would put much weight behind anything Mark Levin says, so it would be hard to prove there is much damage from it. I also find it hard to imagine that anyone will change their mind about Mann whether he wins or loses.
You're worried that whatever is discovered might be taken "out of context" or twisted somehow? Well, you're already going to court over the matter, it's not like you have to find a lawyer and file suit over that. It will be part of the proceedings THAT YOU STARTED.
Whether the claims that were made by the defendant are baseless or not is not entirely clear, and are a matter for the courts at this point. But also as I said, the fact that this is about AGW makes it a fascinating story but is really irrelevant to this issue.
Here's a bit of information that might shed light on the baselessness of the claims. I recall an email from a handful of years ago, after the initial appearance of the hockey stick, from NCAR scientists who were quite giddy with glee that they had been able to modify some of the parameters of the model to obtain a much more significant upturn in the rate of change. It was pretty clear from that email that the goal was not to accurately represent the physical processes involved but to get a scarier result. No, I don't have that email anymore so I can't quote it, but I do remember the message it conveyed. It wasn't "we understand the physics better and here's the new results", it was "we changed the parameters and got a higher rate of increase."
Now, I assume that Mann was on the NCAR mailing list that came out on, and I'd say that were I him, I'd really not want that email showing up in a trial.
Take that as you will.