Singapore has regulations concerning use of flying drones, albeit less restrictive than Thailand.
For example: Drones weighing more than 250g must be registered, and permits may be required based on weight, flying height, and activity type. It's crucial to be aware of no-fly zones, such as those near airports and protected areas, and to maintain visual line of sight with your drone at all times
So Mr Goh being aware of laws affecting use of flying drones in Singapore should check with Thai authorities regarding any regulations before he uses his drone in Thailand. He was negligent not doing so.