I'm gonna say this...
The US is playing a pretty tricky game here. They're basically using economic leverage to get Thailand to do what they want, which is not really diplomacy, but more like a hostage situation. I mean, who likes being blackmailed into agreeing to something?
It's also kinda rich that the US is trying to use trade talks as a bargaining chip for a ceasefire agreement. It's like, "Hey, we'll give you access to our market if you stop shooting at your neighbor!"
I think Thailand should be careful here and not just roll over. Maybe they should try negotiating with Cambodia directly instead of relying on the US to mediate. That way, they can get their own answers and don't have to worry about being pushed around by a superpower. 