Honestly, it seems that US Airways did nothing wrong here. They were proactive about making sure they did not have a medical emergency on board.

As a lesson learned, for you and anyone else reading, if there is some serious medical consideration for a flight, find out the airline's policies before you get to the airport so that you can plan and get the appropriate documentation in a timely manner.

Now, for your question about compensation, I really don't think you'll get too far with US. You can certainly ask. If you do, keep it concise and stick to the facts. Don't include emotions in it and be clear with what you'd like as compensation. They may toss you a small voucher or miles.

The bigger issue I think is your travel insurance. I have no idea what your policy was, but you may want to appeal their initial ruling. There are times where, after more consideration, they do pay a claim. Don't take their first no as a final answer.