We will see, then, whether CBS or the judge disputes the chosen definition.
Yes. That is what we SHOULD be doing. In the meantime, until the definition is disputed (if it ever is), we should stick with Ranahan's definition. Because unless it's successfully challenged, that is the definition that will be used, at the very least, for this motion.
Given the apparently common usage of the term strongly asserts parody, and parody is a key defense for fair use, CBS might take objection to the definition.
Except this is not identifying defenses. It's a technical motion reviewing technical merits.
The court case is for CBS/Paramount to prove their gripe, and the defense to prevent them from proving that gripe. That is not this motion. This motion is saying that CBS/Paramount didn't air those gripes properly.
Usually a motion like this would talk about jurisdictional problems, like, "This isn't the right court to hear this." So let's say that this was filed in a state court, and copyright is based on federal law. Ranahan could argue that this was filed in the wrong court, that it should be in federal court. And a judge would likely agree.
But the ruling doesn't mean that CBS and Paramount were wrong about the copyright infringement claims ... it just means there was a technical problem in the way it was filed.
Does that make sense?

In the meantime, it puts an onus on reporters/bloggers to point out that the definition submitted is not in alignment with the definition which will be found by searching for the term.
From Dictionary.com (http://dictionary.reference.com/browse/mockumentary?s=t)
a movie or television show depicting fictional events but presented asa documentary.
That looks to be quite in alignment to me.