So what happened to archive.today's owner and their data? Was the investigation dismissed?

Was it dismissed?

An FBI investigation isn’t a court case. No charges have been made (that I’ve heard of). They’re trying to identify the person who runs the service first, then go from there. These things take time.

They’re probably operating out of a country where they are legally untouchable for copyright infringement. Or for that matter, just not in a 14 eyes country.