Only if the effect grants a Fort save.
- Immunity to all mind-affecting effects (charms, compulsions, phantasms, patterns, and morale effects).
- Immunity to poison, sleep effects, paralysis, stunning, disease, and death effects.
- Not subject to critical hits, nonlethal damage, ability drain, or energy drain. Immune to damage to its physical ability scores (Strength, Dexterity, and Constitution), as well as to fatigue and exhaustion effects.
- Immunity to any effect that requires a Fortitude save (unless the effect also works on objects or is harmless).
If the Nauseated condition is caused by something they're immune to or not subject to, no problem.
But if it's a spell that simply says "You're nauseated, no save", that isn't a poison, disease, or mind-affecting effect... they're not immune.
-Hyp.