No it isn’t. From Blizzard Support:
Groups are empowered to manage their own members through the vote-kick system. If the majority of the group feels a player should be removed, they can initiate a vote-kick to remove them. The system is entirely under the control of our players. Players may choose to remove any other player from the group for any reason, provided the vote to kick passes.
Even a quote from Vrakthris on the issue when people came to Customer Support