I kind of doubt anyone would be familiar with O'Shi'ur. Tau lifespan is relatively short, with old age starting at 40. He only has the XV22 because he has a flawless battle record and passed every trial by fire on his first attempt. I have his age at about 33, so unless one of your characters has been near the Damocles Gulf in the last 5 years or so, I doubt O'Shi'ur has met any of you.