I recall literature indicating the system is kinematic a member of the thick disk, and it looks like spectroscopy confirms its age.
The discord between activity-derived ages and other methods of aging for stars with white dwarf companions is becoming an increasingly noticed phenomenon; I don't recall it being significantly physically evidenced prior to the discovery of
HD 8049 B, but the effect has since been noted for
HD 114174 (companion discovery paper
here) and has now been characterised for Gliese 86. It will be interesting to find out what the limits to the separation between the main sequence star and the white dwarf are in order for this to take effect - maybe 40 Eridani, with two MS components at 35 and 400 AU from a white dwarf with a cooling age of ~0.1 Gyr, will be a useful test?
That mass for the WD progenitor puts the pre-evolution system as loosely similar to Alpha Centauri, though the differences in metallicity mean that neither system is a perfect proxy for the other. Still, it points the direction in which Alpha Cen will develop, I suppose! It also puts into perspective how weird Gliese 86 Ab is; how
did such a massive object end up in a 16-day orbit in such an old system? Using the Alpha Cen proxy, B's protoplanetary disk is supposed to have been truncated at just outside the ice line, which pretty much cuts off giant planet formation; so how did at least 4 Jupiter masses end up coalescing in a similar system? Gliese 86 is certainly a system worth further study!