- Also very common: men drawn in by an attractive 'date' then assaulted, robbed, sometimes drugged by them or their accomplices. Rarely someone might be killed.
- Gambling gangs/extortion - make friends with some friendly young foreigners who are on holidays, invite them somewhere, start with a friendly card game that gets progressively more threatening. March them to ATMs and demand money and maintain control of them until they pay.
- Taxi driver incidents: If he was enroute to the airport when his phone pinged, I hope Simon didn't get in an argument with a taxi driver. There are some pretty vicious taxi gangs out there and it's known that it's one of the few jobs that ex-prison inmates can easily get. Usually it's Thai people affected, but this was a historical, quite well known instance involving a foreigner
www.bangkokpost.com/thailand/politics/359730/aftermath-of-expat-killing
- Maybe he's arrested and the Thai government are just taking time to notify the British Embassy. IMHO that would be highly unusual, Bangkok police are usually pretty good at letting foreigners notify their embassies if they are detained, particularly in Bangkok.
Honestly based on the numbers I dealt with over a 4 year period, statistically I'd guess mental health issue, though it's obviously impossible to say given the limited information we have here.