If the QR procedures in BKK are anything like the RJ procedures in BKK then no. On RJ, there is a Boarding Pass check conducted when you get off the jetbridge in BKK and they cross check your BN with the manifest, cross your name out and only then let you go. There also ground staff running around and counting pax with the counter before the passengers from BKK start to board.

You can definitely not short check your bag to BKK only. Obviously, if you tell them you are not gonna fly, they will not ddetain you, but there will be some complications.