In Australia, I believe private health insurers use a shared-risk model.

Basically, they cannot deny anyone insurance based on health/age.

Once a year, all insurers submit their claims data to a central pool. They will then need to pay a certain amount to the pool, or get a refund based on their claims vs the rest of their providers.

That means risk is shared between all companies, and they don't need to deny people plans like in this case on the chance they get too many "bad customers".