I would not buy a FIDO2 token if it allowed anybody to reprogram it, including me. If you managed to make selling me such a device illegal, then may a pox descend on your house.
You're free to choose not to reprogram it, so the pox is actually upon your house.
Also, you should probably spend more time reading about cryptography and less time reading FIDO Alliance propaganda.
If I want to reprogram my own FIDO2 token, I should be allowed to.
If I get your FIDO2 token and reprogram it without somehow also wiping the data on it, your problem is that I got your FIDO2 token, not that I could reprogram it without erasing it (which theoretically could perhaps be true right now)