Board Thread:Episode Discussion/@comment-14138255-20160225225013/@comment-410526-20160314182816

Inclusion in the group seems to be based on Ozpin's discretion only. Qrow states Ironwood is only a part of the group because Ozpin wanted him there. Presumably this means that if Ozpin wasn't cool with him, they could have left him out of the group, despite him being a headmaster of an academy.