“zmessenger-dev” is, I believe, the “alt account” they lost the login info to. Their main account, presumably tied to their identity, was used to author a commit that was pushed the DMCA’d repo. They later lost access to the alt (zmessenger) and so cannot remove the repo.
This is possible since GitHub attributes commits to certain accounts based on the email that authors the commit, so they used an email tied to their main account to author the commit. Only the email is actually attached to the commit though, GitHub just associates the account based on a lookup. They then push the commit to the repo using their ssh or password authentication for zmessenger, which they later lose, and so they can no longer alter the repository and remove the offending commit/email
This is possible since GitHub attributes commits to certain accounts based on the email that authors the commit, so they used an email tied to their main account to author the commit. Only the email is actually attached to the commit though, GitHub just associates the account based on a lookup. They then push the commit to the repo using their ssh or password authentication for zmessenger, which they later lose, and so they can no longer alter the repository and remove the offending commit/email