o dear the tree got hungry and ate that chain. Must've had an iron deficiency...
Pretty straightforward on the remedy; per the BMPs brace maybe 3 rods and at least one cable. Or remove and replace. If the owner was open to both I would bid both and let them decide. The support is much more fun and rewarding for me, even if the $/hr is a bit less.
Hackberry has a poor rep re codit but that specimen seems pretty high-vitality so I'd be comfy with installing support and monitoring every 1-3 years depending on how it looks inside.