You are so far off the reality chart, so it makes it hard to know where to start. First, you must understand that we are in Thailand and talking about Thai hospitals. You can not, just walk out of a hospital without paying. Especially not regarding such amounts. You will either be stopped and police will be involved or you will be prohibited to leave the country. This is not American, French or Swedish laws. Here they rely on the Thai law. That one and some regulations says they are obligated to treat Thai citizens, but not uninsured foreigners.
You have confused it all with the thing that says doctors are sworn to save life. That is true, and that is why they are giving him treatment and doing what they can to save him, despite they are aware he can´t pay at the moment. That does not mean he can avoid paying. That does not mean, he will have protection from the law if he tell them to stick it and try to walk away without paying for his treatment. As he have left the security of his home country without a travel insurance, he will automatically put himself in the position as the person who must pay or raise as well as call somebody to pay his debt.
Responsibility in hospitals in this country is very low. Just take when a child is born. Directly the nurse comes with a book, where you have to sign you take the responsibility for the child for the next 2-3 days in hospital. Have own experience from 2 times. However, rather irrelevant, as it had to do with the payment.
Regarding the payment, we can take American hospitals as an example. They are obligated to treat and save the life of an uninsured person. However, many will ask for payment up front, which you can refuse, and they still have to save the person. That, however will not mean they will not charge you. Due to the financial system in most countries, the hospital will also let you go but mostly that is done with their citizens and harder to do with tourists. The reason why they can let an uninsured person go home, is that they have bill sending systems, credit check systems and much more developed systems for payments and economy.
Thailand do not have good systems for this, and therefore they will keep a person in hospital or in the country until the bill has been fully paid. As there are not many foreigners that get into these problems compared to hospitals, there are no hordes of people dying in hospital foyers. The reason for that is the hospitals are full with sick people that are on the 30 baht scheme.