I suspect most manufacturers would designate their hardware for grinding only coffee beans, for liability and/or warranty reasons if nothing else. Mazzer also mention "purpose" in the manual, if I recall correctly.

For what it's worth, I did come across one post from HG One about breaking in the grinder's burrs using Minute Rice.

Here is the Bartatza blurb. You decide.
http://www.baratza.com/rice-its-just-no ... -cleaning/