@Martin *******
we are not talking about the entry requirements. :O
This topic is ONLY what is required if you come in on a visa exempt entry and apply for an in country 90 day Non-O visa and then a year extension.
What ever the entry requirements are don't affect whether you need insurance to buy that Non-O visa and a year extension inside the country (no matter if you held a Non-OA visa/extension previously or not). ..