You can't legislate out stupidity and irresponsibility. Any large dog who has not been trained and/or abused can be dangerous. Especially to a 2 year old child! I've heard about and seen many instances ending in serious injuries from Thai dogs. Especially when they form packs. We've personally saved and rehabbed 21 Thai street dogs, and rehomed all but 2 of them. There are some we come across that are, and will always be aggressive. Nothing you can do. Most vets here won't euthanize either, even under dire circumstances.
Laws need to be directed towards the people who "own" dogs, and education of animal ownership should start at a young age. But the other problem is making sure those laws are enforced, and we all know how that goes. Thais think that letting dogs roam free and feeding them occasionally with no regard to vetting and sterilization, is acceptable. (Unless it's a small, fluffy dog of course).
This guy should receive a stiff penalty and I agree with euthanizing the dog. Not because of the breed, but because of the behavior he's learned. I highly doubt either will happen though.