They should be banned or at least get a warning.
Team in FFA
I wouldn't be surprised if there were buddy systems with three or even more participants. A bunch of jerks forming a circle of sorts.... I suppose one might call them "circle jerks".
As has been discussed elsewhere, were chess.com to publish (or analyze internally), a history of game results (participants' finishing positions and number of moves), the win-loss patterns of cheater accounts would be easily detectable: repeated cases of 1-2 finishes, with relatively low move-counts of opponents, for two accounts anytime they're in the same game.
There's not even a need for draconian measures like banning or reseting ratings. The system of cheating would be easily thwarted by tweaking the "match players up" algorithm to prevent suspected circle jerk accounts from being matched up in the same game.
Here is an obvious case of deliberate planned teaming-up in FFA (red and blue, but it could also be the same person with two accounts).
What can be done against this?
Replay of the game:
Here is the chat: