The column does not exist in that table, should be fetched from the
rdfs:Resource table. This results in the query returning the column
name as a string (due to the quotes), and turning out as a 0
nao:lastModified.

Those dates are kinda thrown away for readwrite connections, so it
didn't matter there. They stick around for readonly connections in
the internal TrackerOntologies, but the modification date has no
use or purpose on those.