If I remember correctly from phase 3 doing this fate, it's a fate that is situational. If Keeping or Defending fails then the wood wailer's npc's die and it's taken over by redbelly npc's. I think it's redbelly anyway. From there the next fate in the area becomes Clearing the Hive as the goal is to recapture the area.

It's actually a fairly difficult fate if you do it at appropriate level and aren't super zerging it. Because of the way all fates in general are getting super zerged it's unlikely you'll see this fate even pop up as long as current Fate spamming stays around, the other Fates just aren't going to be failed.