The idea that the OP is at fault for looking at data which the city had already published has no basis in law.
This simply isn't true. If someone accidentally sends you information that you know you shouldn't be privy to, you should delete it. Unless perhaps you are Nelson Muntz.
Having legally downloaded the data he looked at it. There's no crime there either.
The idea that the OP is at fault for looking at data which the city had already published has no basis in law.