We will not cover the following:
2. Any treatment or surgery which we think you do not need immediately and can wait until you return home. Our decision is final.
That's what travel insurance is. It's there to pay for care until you can fly home. Accepting their flight home isn't voiding your insurance. It's getting the coverage you paid for.
Furthermore, the policy says clearly, until I CAN fly home. My DR had explicitly told me I could not. I wasn't going to risk my health for the sake of my arsehole insurance company and their bullshit attempts to wriggle out of paying.
Ask yourself, would YOU have ignored the advice of your DR, who knew your case personally, in favour of the "opinion" of a private company whose sole motivation is financial?