There has tended to be some ambiguity about the reach of Thailand’s Computer Crimes Act. But according to this post, which piggy-backs on the original translation from, the official line is that:

If there is anyone who starts a website outside the country to distribute information disgracing the monarchy, destroying the security of the juristic system or generating fear among Thai people, the wrongdoer will be persecuted by law and receive penalties inside the Kingdom of Thailand.