I don't remember asking that question, maybe JB or CH did, but I made the assumption that it was for flavour and to help stop the rice sticking together. I will ask next time I'm in there for a meal.
Something which impressed me about all the dishes I saw prepared was there were absolutely no shortcuts, no dumbing down or omitting steps to reduce costs. If they think something will improve the flavour of the food they do it, painstaking as it may be. They are clearly striving for the highest standards, not the lowest costs. That's why I consider this place to be the best in my local area.