There have been some additional verification steps put in place for group names that may be restricting certain words or phrases that weren't restricted before (i.e. before the beta version of Bungie.net was rolled out). The reason for these additional steps is because your group name will appear in-game on your nameplate if you set that group as your clan, therefore there may be additional standards to follow set in place by Sony or Microsoft. Tl;dr you'll probably have to choose a different name, sorry.