1. Actually if there is no such reg listed in Timeatic then there is no reason that they should have rejected the OP.

2. What is written on the US state department site is ABSOLUTELY WORTHLESS in this case. What is valid what the Thais say and what is posted on Timeatic.

3. Your passport is valid for 10 years especially as the US has treaties in place with most countries that make old school boilerplate 6 month idiocy irrelevent.

4. In such situations all one has to do is indemnify the airline in writing in case there is any possible fine or repatriation expense, and that "covers their butts". I have found myself in one or two of these situations (generally when dealing with morons) and this has always sufficed.