If you are not a US citizen your payments will stop after 6 months and you have to return to the US for an entire month before benefits start again. The wording says you must be in the US from the first minute of the month until the last. US citizens receive payments indefinitely and do not have to return. Thailand is listed as one of the countries that can have payments sent to.
In all the information I have gathered I never cane across that requirement. I do know that medicare will not cover outside the US and was advised by one retirement planner to try and keep paying medicare B incase you have to return to the states for care. When you return regular medicare will cover you in the states.
Someone correct me if wrong but Non-O visa does not require health insurance and you get that visa inside Thailand and OA visa requires health insurance and you get thst visa in your home country before leaving.