First, you are way too late, this has been brought up since that vote was completed. Second, we're no longer in the part of the quest where the votes represent objective reality; the choice wasn't pick one object and let the other fall into the void, because if they were both there, they would have been prioritized over literally everything else in that room sight unseen. We were making a choice on which of two possibilities the loot waveform collapsed into. Third, with the fullness of time, Grandmistress Lei's works would have resulted in much less favorable opinions among the court of the Emerald Seas, as it would have kickstarted the song cultivation part of Ling Qi's cultivation, and thus would be worth more to her in cyan and beyond than stones would be, so we'd keep them. Because Ling Qi doesn't care much about the tapestry and the geneology, selling them to notable buyers lets her "give back" and reinforce the idea that Ling Qi, as an extension of Cai Renxiang, is actually working for the betterment of the province rather than her clan.