See tracker-miners#155 (closed) for background.
Currently Gio behaviour is undefined when querying creation or access time for a file, if the time is before UNIX epoch (1/1/1970). Apps can either interpret the guint64 as unsigned timestamp, which gives wrong datetimes way in the future, or interpret it as
time_t and depend on undocumented, platform-specific behaviour.
In Tracker Miners we are planning to depend on the undocumented behaviour to enable a quick fix for #155, migrating to a new GDateTime based API when possible. We'd like to avoid any unnecessary changes in the existing behaviour while we migrate to the new API.