He heard from a very reliable source that the Thai government tightly restrict everything to do with helicopters because they are afraid they may get into the hands of drug growers/manufacturers who will use them to fly into remote areas. May be just a rumour but it wouldn't surprise me.
Why do people always think drug smugglers or criminals in general would care about laws in the first place? If I'd be one of them, I'd get my R22 if I need it to fly my dope out of the bush. Who cares what the government says if you are producing drugs and the government is after you with guns???
Another reason that speaks for the Cabri, it's apparently silent and has a luggage compartment
PS: How about "transiting" through Thailand with N-registered helicopters?