I'm going to take a guess and say it was because the eye witness identified Ronald Cummings and his vehicle. Of course, if the second person was interviewed by the police, I am at a loss as to why that person's name wasn't released, as well. Could it be that, since the passenger wasn't identified as having put something into the mailbox, that person's name is protected? I mean, that person isn't stated as having (ALLEGEDLY) perpetrated an act which could be reasonably perceived as intimidation, not to mention a federal crime by using the mailbox, only Ronald was identified as having done so.