No, the wires do not become less dense.

There is a virtual force acting to separate each part of the chain from each other part, but locally that force is orders of magnitude less than the bonding forces holding it together. The structure and density of the chain is therefore dominated by electromagnetic forces, rather than the expansion of space.

At large enough scale the expansion force will grow to become comparable to, or exceed, exceed the binding forces. That will cause the chain to stretch, but the electromagnetic forces will still exist and still be applying a restorative force trying to contract the chain again.

I’m pretty sure this requires many light-years of chain though, unless the acceleration of the universe is accelerating (in which case this same principle will eventually tear apart all matter, of any size), and I very much doubt that physics allows a material with the necessary properties

snag bites of the apex predators

I don’t think the author knows what “apex predator” means