Unfortunately, I don't have the required medical knowledge to provide a definitive answer. However, I can provide some information that may assist others with more detailed knowledge. Here's the best detailed information I could find regarding the pharmacological properties of Olanzapine:
Olanzapine 5 mg tablets - Summary of Product Characteristics (SmPC) by Aurobindo Pharma - Milpharm Ltd.
www.medicines.org.uk
So, it exhibits a range of receptor affinities, specifically 5HT and dopamine antagonism, which is required for SN. However, to what degree is not clear compared to meto or domperidone, so required dosage is difficult to say. It also doesn't appear to have gastro-prokinetic properties, which the recommended antiemetics do and which produce rapid stomach emptying into the intestines where absorption occurs.
It is used as an antiemetic for nausea induced by chemotherapy.
That's about as much as I can contribute.