u/ArcticShore

In the new update several bosses were omitted from the boss rematch feature likely due to the unique circumstances that you fight them like the 3 'tracking' bosses, Muskan, or Goldstar.

Tervis here however, has no gimmick to his fight that would make him unsuitable but instead I think that they just straight up forgot to add him lmao. A boss so easily missed and so easily forgettable that even the devs straight up forgot to add him.