OS X has always suffered from all-to-common misreading, however. They traded that for a likely-to-be all-too-common miscapitalization/misspacing.
If it was really meant to be "OS 10", then they wouldn't have versions like "OS X 10.6", they'd just have "OS X.6" or "OS X.VI". How many people do you hear saying "OS ten ten point six"?