I don’t know their situation but common tactics are to deny claims hoping that the patient will either die or find other funding options. This is an entire industry:

https://www.propublica.org/article/cigna-pxdx-medical-health...

https://www.propublica.org/article/evicore-health-insurance-...

This is one example of how hard it can be to fight these fraudulent denials, even for someone with above average resources:

https://www.propublica.org/article/priority-health-michigan-...

Individuals can’t fix these problems at scale: it needs something like a government investigator with subpoena power and the ability to directly fine executives. As long as people make more money by denying care, they’re just going to keep finding ways to do so.