The HZ were serving as the default Wakandan red shirts goes all the way back to Hickmans New Avengers run, so that's not a Coates thing. Course, it's entirly possible Zub ignored everything Wakandan related since then in comics... but either way it still kind of works since White Wolf and his HZ being independent of Wakanda is a real thing. Just a thing which has been ignored for a long long time.