Its understandable that there is so confusion in looking at the current scene in the thai bare knuckle arena. There are several lines to the situation and some might be more problematic than others.
General Amnat is really about bringing the old Thai texts of strategy, philosophy and science and using the bare knuckle systems to illustrate them. So he is using a generic template of techniques from the various old systems. A chiaya person might complain its not detailed as to the way they teach or a korat person but thats not the point really. His work is important to understanding the relationship of texts like the pichaisongkram and their relationship to the thai martial arts which would be hard for a regular foreigner to get in english. When linking them or showing them in comparison, he is bringing out the highlights of these systems for those who want to further investigate them in detail or pursue the study of the strategies or texts that run through them.
In grade schools into college phys ed, they have a program of "muay Boran" which means simply old or ancient boxing, where they grafted together a program from the various old bare knuckle systems as a way to use it as a safe physical activity that at once supports the thai cultural heritage as well as surviving in as a form of performance or activity. We see alot of foreigners in europe and the us gravitating toward this as the true be and end all when its just what it is, a mishmash of techniques without a defining root and strategy( meaning in korat, the structure of the stance and techniques follow the strategies of the style same as muay chaiya has its own distinct strategy and way of fighting and mae mai/look mai).
Muay Boran of course would be a term used for any of the old systems from tao sao, chaiya, korat, etc because it simply means the old ancient way of fighting which all of them are. When the old systems were active, they were just muay or fighting. For clarity, I leave muay boran distinction for systems which use a template of the various systems in a generic fashion and just use the actual names for the rest muay chaiya, muay korat etc since each is distinct and has a name which is exact to what it is.
Many of the chaiya people consider their system not only a complete system like the others including korat, tao sao, sakon nakorn, etc but also a form of cultural preservation. There is also confusion emanating from within muay chaiya with several teachers vying for a type of "grandmaster" mantle and using the internet for arguments and infomercials of varying degrees which adds further to the confusion. There are many good teachers of chaiya who continue the tradition in a pure honest way without any fanfare. Those who are interested in the system can seek them out with some effort and will find them more than capable of teaching the system in a direct manner.
Some people on websites and articles continue also to use old information like tao sao is off limits to foreigners and various other things like that which is old and not applicable anymore. They are just translating old texts or articles and generally have not trained in the systems or have updated the material through research.
The main thing for me in my training and my research was on finding the last of the masters who could apply these methods and produce the system that allowed a person to use them in the actual fight. So my approach was to find the utility and function with them which has been downgraded since many of the masters dont produce students that fight or steer the programs toward that much anymore. So again, if someone approaches it in that manner he might be met with several roadblocks and confusion as to what avenue of these systems is he learning.