This is more or less than same lawsuit thats been happening for a half a decade. Its not really new.

They were already suing them, and then some additional info came out in discovery related to the Darabont suit, which help Kirkman and other's cases regarding AMC purposefully not respecting their MFNs, and then AMC and Darabont got finished and now they are using that to try to close out their suit.

Basically nothing really new here is happening, they're just doing regular legal things that need to be done to get AMC to the table again