Vote-kicking players will no longer be possible while loot is being rolled for or while players are in the middle of a boss fight, thus preventing two rather common forms of griefing. The change will be rolled out shortly before the Strongholds patch on the PC, with an Xbox patch and announcement coming “soon.” Hopefully, this will curtail abuse of the abuse-prevention system, because nothing is ever easy.
Source: Changes coming to Vote-to-Kick