I have been concerned about this as well, and I do agree that they would be violating the license if they refuse to provide the full source code to anyone they’ve distributed the object code to (effectively anyone, as they publicly offer downloads of the firmware images). Klipper is licensed under the GPLv3 without any sort of linking exception, so those modules are derivative works.
That said, I haven’t asked them yet, as I haven’t had the time to draft the sort of e-mail that I would hope has any chance of a productive response. Have you asked them, and they’ve explicitly refused?
I did find another thread about the K1 (Creality violating Klipper license?), and specifically this post by @koconnor confirming no dual-licensing had occurred, at least at the time of that post. When I last checked, it looked like the K2’s Klipper is an older version, likely the same codebase as the K1, so I’m guessing nothing has changed.