Apart from anything else, making Thailand a safe haven for same sex couples is a no brainer economically.
The list of nations who still persecute gays is too long to publish here but neighbouring Malaysia, most Middle East countries, Russia and China are enough to start.
Whether as a holiday destination or a permanent home for retirees there are clear benefits to the Thai economy in the long run. The more welcoming the better, IMO. It's not as if the economy couldn't do with a boost now.