Depends on what you mean by "knows it".
If you mean recognising it, then I don't think you can jump to "he doesn't know it". I'd say most people think there is a difference between Ryuo with swordsmen and non-swordsmen. If you carry over this logic for Adv. Ryuo, then it would make sense why Zoro hasn't seen it from a non-swordsman so far given his training.
If you mean actually having that type of Ryuo, I don't think he has it, but I don't think that statement reveals he doesn't have it.