Understandably and I concur. However, I haven't met anyone outside of the apple company that would pronounce it OS 10. That being said, they don't even use the nomenclature anymore.
I came over to Snow Leopard from Windows and always thought OS X til I heard it at a WWDC. Later, I met professors that had used OS 9, System 7, etc. and they always said OS 10 consistently.