Confirmed last night while playing MM with friends. If you’re host, you can select the player from either team in the scoreboard and boot by pressing A and selecting kick. The player is then kicked out of the session.
Awesome
Before anyone says these are dedicated servers - http://venturebeat.com/2014/11/13/microsoft-explains-when-halo-the-master-chief-collection-uses-a-dedicated-server-or-peer-connection/