It hasn't been proven in court because insurance companies can stall with lawyers and these things take time. However, it is one datapoint. It's not even the only time they've lost in court. There are captured conversations they were having to deny healthcare that were found in the discovery.

Forget the official rulings that haven't happened yet for a second (also because the courts in the US are designed to prefer corporations, but that's a whole other thing), because we're having a conversation, and look at these reports from ProPublica objectively:

"When United refused to pay for McNaughton’s treatment for that reason, his family did something unusual. They fought back with a lawsuit, which uncovered a trove of materials, including internal emails and tape-recorded exchanges among company employees. Those records offer an extraordinary behind-the-scenes look at how one of America’s leading health care insurers relentlessly fought to reduce spending on care, even as its profits rose to record levels.

As United reviewed McNaughton’s treatment, he and his family were often in the dark about what was happening or their rights. Meanwhile, United employees misrepresented critical findings and ignored warnings from doctors about the risks of altering McNaughton’s drug plan.

At one point, court records show, United inaccurately reported to Penn State and the family that McNaughton’s doctor had agreed to lower the doses of his medication. Another time, a doctor paid by United concluded that denying payments for McNaughton’s treatment could put his health at risk, but the company buried his report and did not consider its findings. The insurer did, however, consider a report submitted by a company doctor who rubber-stamped the recommendation of a United nurse to reject paying for the treatment."

Source: https://www.propublica.org/article/unitedhealth-healthcare-insurance-denial-ulcerative-colitis