Hi Veltins,
Sorry to hear about your loss, especially as it was so unexpected.
There should be more regulation when it comes to travel insurance. They are required to ask about medical conditions in order to assess what might be the correct package for you, and charge an additional premium for any higher risk persons travelling. I'm no expert in this line of insurance, but medical questions are usually always asked when you obtain quotations over the telephone. On the internet, or even in the shop, they might hand you a form and ask you to sign. What with the excitement of it all, sometimes things can be overlooked.
I appreciate where you are coming from on this entirely, but I do feel your trip to the Ombudsman might be a wasted effort, although I hope otherwise.
Good luck!