Should this title be updated to "Tracking a single person through wastewater viral RNA"? The SARS-CoV-2 genome is RNA [1], and this is presumably what's being measured by this virology researcher. The tweets don't specify DNA or RNA, but from context it seems they are tracking the viral RNA.
This also removes some of the spooky surveillance overtones, since the genetic material being tracked originates from a virus, not a human genome.