Board Thread:General Discussion/@comment-24159286-20131112052402/@comment-6746577-20131121024455

Ten Tailed Fox wrote: Because Grimmjow is a Hollow (Arrancar are still Hollow at the core). Hollows go against everything Soul Society stands for. All of it. The Central 46, much less the Shinigami themselves, will never allow a Hollow in their ranks.

and yet, the Royal Guard trains Ichigo who is 1/4 Quincy and 1/4 Hollow