I really need a throw away line explanation.
for fans and professional tie-in novelists to extrapolate?
Where have you been for four decades?
Well no, but it was a good oppertunity to put them in there, instead we get two random new aliens.
Two members of the same
species, weren't they?
Had Caitians been used, we'd have people screaming, "But Caitians were in ST IV and ST V. Show us something new!