Seeing that rice wine or sake is made through the fermentation of rice, which as we know is a grain like wheat and barley, is it on topic here? Why is it not called rice beer? Wines and ciders are the result of fermentation of fruits.
We've had similar questions regarding Cider and Mead and in both cases, the top voted answer opines that they should be on topic.
So, my personal opinion is that it should probably be on topic, at least until some point when we decide that it no longer fits or have a better site for it. At this point, it would be my opinion that rice wine questions would be fine here.