The DMCA safe harbors have a requirement that in order for an online service provider (eg the ISP) to be protected from liability for copyright infringement that the ISPs have a repeat infringer policy to (eventually) stop the copyright infringement of their users by discontinuing service to them. Without the DMCA safe harbors the ISP would potentially be on the hook for copyright infringement. With high statutory damages for infringement, that’s a lot of potential money for the group suing the ISP, hence why they would want evidence showing the ISP didn’t have a repeat infringer policy or did have one but failed to enforce it. Testimony from a pirate saying how great the ISP was because they didn’t ban them even after multiple notices would help establish that.