From the Epilogue map:
<Dialog branch="23">
OnTurn/0//Silithis, carefully observing how Emma had been interacting with her men, began to pay more attention to her own manner of speaking. She strived to be more observant of others' nonverbal cues, and to be less rude and dismissive.-N-After extended discussions in lissit, Silithis eventually convinced a hesitant Sarn Kamina to return with her to the zaris to be reunited with her mother, Ambuur Sang.
<Action>IfValGoTo/SarnDead,=,1,24</Action>
<Dialog branch="24">
OnTurn/0//Disgusted at her own failure to protect Sarn Kamina, Silithis left the mines and returned to the zaris in disgrace.
<Action>IfValGoTo/SilithisDead,=,1,25</Action>
If I'm reading this correctly, the game will only skip both of these if Silithis and Sarn are dead. It doesn't look like there's anything to block branch 23 if Sarn is alive but Silithis isn't.
Ah! Good catch. That's now fixed for the next patch.