Yeah, that bit sounds more like they have a faint hope that someone high enough up the ha family tree (probably one of the twins) gives enough of a crap about jinsung to make moves. While its remarkable that jinsung is acquainted with multiple family heads it's a bit difficult to imagine any of them giving a crap about him. Including yurin. With the sheer lack of familial bonds in the great families it's even a reach that the twins would care about him either as a son or nephew. Let alone the old lore implication that the ha family had a matriarchal structure. Maybe jinsung is so old that he was around at a time where the twins would still see a son as special (I am assuming that after a few hundred babies they sort of lost their ability to care/remember). I suppose there's also a chance that even if the twins are not particularly interested in jinsung there's still brothers and sisters from a time where that would have had some weight. Or perhaps even without brotherly bonds he made friends with ha higher ups... It's ultimately a stretch that family heads would move an inch over having met jinsung however long ago. To me it's also a stretch that jinsung is lobadon's age... To me he feels younger than the genesis war.