I'd call up Delta and start demanding denied boarding compensation. You might get someone high-up enough to deal with it.
Your onward flight itinerary should be more than enough. Offer to have a conference call with the Thai consulate. Raise a stink.
Besides, TIMATIC (the electronic version of the Travel Information Manual) is not designed to be comprehensive. From
IATA's website:
Can TIM be consulted for all travelers?
* In general TIM should be consulted for airline passengers traveling for tourist or business purposes. TIM cannot be consulted for immigrants, persons wishing to adopt children, to study or take up paid employment abroad or individuals crossing borders overland. Those passengers should be referred to the consulate of the country concerned.
The Thai consulate is the authoritative source; not TIMATIC.