Good find. Footage not used in the finale. Perhaps they have already filmed some scenes for episode 1 of season 5.
Yeah, the comment/write up that goes with the pic hints at some things.
one, that they clearly are cannibals.
two that the chained walkers are former terminus folks that are still “useful” to the living terminus folks in their path “a” and “b” routes of strangers.
three that the terminus folks feed their chained walkers to keep them stronger/more of a threat to those running the A or B routes.
and four, my final opinion is if the chained walkers ARE former terminus folks that died/turned, if the terminus guy who just got shot (Alec?) doesn’t survive, he’ll wind up there, as I don’t believe the terminus people eat their own. they eat outsiders.
five, hints at what the terminus group’s been through and their experiences with outsiders. they probably had trouble with outsiders and lost a bunch of their own (now their chained-up walkers since they were THEIR group, not strangers) but their group won/survived. if newcomers are friendly and go along with everything that’s going on there, as they learn more, they may join, but at the slightest sign of not going along, they become a threat and are turned into food. and from that pile there are a lot of people who do not go along with the core terminus folks.