[Norfleet]

No, it's because the Nataraja isn't a Caelian, and therefore has no innate cold resistance. If you give him a cold resist item, that encumberance penalty vanishes, as anything cold resistant suffers no penalty for cold. Caelians also appear to suffer no penalty, perhaps because they're all Cold Immune. Are Raptor Caelians immune to the fatigue penalty also despite not being cold immune?

However, the Nataraja is NOT a Caelian at all, so doesn't benefit either way.