Your “friend” will likely be denied coverage by all of the 14 approved Thai insurance companies due to pre existing conditions. In my experience they will not offer exclusions, they will simply deny coverage.
Then, you will have to answer the question, “have you ever been denied coverage?”
Better to apply for a Non O extension based on retirement from within Thailand.
Then, you can purchase insurance from any company, anywhere in the world, that will cover your “friend” within Thailand and you don’t have to leave Thailand if your policy gets cancelled or renewal denied.