Silly government workers. Go to all that trouble to try and hide the identity of the person under investigation but forget to redact the email address associated with that person, which happens to have his name in it?
See, this is why you have to consider any and all personally identifiable information when you’re looking for things that need to be redacted, including variations of email addresses. This is a silly mistake by the government, but one that probably gets repeated in less public cases on a regular basis. Stop and think about all the information that could be used to identify someone before you make the data public.