I found it very interesting. He basically politely says that what MCTB and the like consider to be awakening is not the same as how it is understood in Thailand or Burma. He does end with a nice story, though, on how the different views and approaches are all a valuable piece of the bigger picture.
Wow. I'm surprised he's willing to speak for the perception of 'awakening' for the whole of Thailand and Burma.
However, there's predecent, like:
In his book
Modern Buddhist Masters (he
found only males to exhibit*edit: As "masters", Kornfeld found 11 males and 1 female),
he wrote,
"Outwardly they [the masters] may seem different, even contradictory. (...) These words and systems are simply different expressions of a single underlying truth. Dhamma does not change. (...) so the words and teachings of these masters all point to the same experience, same truth."
(exerpted from page 2; I have not materially redacted his meaning just left out a short sentences and poetic analogy in a short paragraph).
That's quite an authoritative statement.
(And it's a statement I really would not say; it assumes vast and complete knowledge that has not been inventoried to verify -- and the teachers themselves note that others among them do not have complete/right awakening!).
So Kornfield may now, again, be speaking authoritatively for all of Burma and Thailand, as you note, just changing his opinion-- that not all teachers and systems are teaching the same truth.
It may relate to necessity, as he and Ms. Brach are selling a new "Regular Price
$397 Today $297" series (that's how it's sold at present online, with a line through the higher price for emphasis on the brevity of "today" (it's been promoted like this for many days))...
..and commercial meditation teachers face a very crowded field of co-vendors today.
It may be that from the commercial side he feel he needs now to differientiate himself from other brands and that he no longer feels "all these masters point to the same experience, same truth."
What I liked about that book,
Modern Buddhist Masters, is that he presented teachers who are deemed masters as contradicting one another about what is awakening, what is jhana, etc... and so this book was a great way for me to know early on to do the practice plainly for myself; not to look for coaching, validation, authority in someone else's journey, plan or (changing) understanding.
As seen, teachers/coaches/etc change their minds and when they do, then what has one practiced and bought into?