Yes, 2004 saw the first public release of OS4. But it had already been in development some years before with internal drivers, so pre-9250 Radeon, Voodoo and Permedia 2 cards is what "they worked with" during that time. Besides, the earliest official mention of the 9250 in OS4 context I could find is this from 2006 about the 5th public OS4 release:
