LinkedIn says they left February 2016. It's actually been awhile now. Woulda' thought we'd hear the cheering from Beyond over this way when it happened. If Brian Reed left I think the Halo story reddit would be audible from space.
EDIT:
Looking at their site (guys, I know it's early, but work on that logo!) looks like in addition to Franklin, the team includes Halo 5's multiplayer engineer, multiplayer designer, and lead multiplayer producer.
It's nice that Walshy has a job in the industry now. You could tell he was a bit frustrated he hadn't been able to break in.