Now you're just being silly. And, IMNSHO, completely and utterly so.
- Pattaya is pretty far from the Islam-dominated Malay areas of Southern Thailand, which is the area of Thailand where there has been any Jihadist attacks.
- Malay Jihadist actions in Southern Thailand have historically been of a completely different type.
- Killing a single tourist, without any public statement, is one of the more stupid ways to perform terrorism. That sounds like something that Jesús Bernal from the "First Weekend in July Movement" could have done in a Carl Hiaasen novel.
So, in short: There's absolutely nothing - except in your fantasy - that indicates that this was anything else than a run-of-the -mill criminal murder. Even guessing about something more sinister than that is ridiculous. And
assuming that it's a Jihadist action, just because the victim's throat was slit, takes the whole supposition beyond the ridiculous and well into the absurd and surreal.