You can’t get a visa to work in/from Thailand (except Volunteer visa) but Retirement, Elite, Education are all ways to live here long term pre COVID. Who knows whether they will continue to be when the country opens again.
he says the flight is originating from BKK. He won’t be allowed out of arrivals (from wherever he’s flown in from) to check in for that flight. In fact it’s unlikely he will be allowed to board at all without documentation to do so. He’s not ‘in transit’ for a connecting flight.