AkshatArpit
Well, I don't find them useless at all. The queen even wanted him as king, while he was super weak. Having the Nagas in their team and under Arnold's rule is very beneficial - he can have a super adapted and loyal (If he does it right) force in the swamps - win-win for everyone. Not all monsters are mindless, being overly racist does not make things better. The world has changed after all. Devon understood that and banded together with the Lizardmen. They are even compatible on a genetic level, I'm sure there are some men looking for beautiful wives. Arnold might be a champion of monogamy, so having other partners beside Nina would be difficult - (for the king & mate thing). But under the current circumstances in the world, a cultural mix among intelligent species is probably the best outcome.