>The thousands of winre thumb drives are certainly out of reach; maybe the bitlocker side update the access permissions? Would it require unenc/reenc?

The part that isn't mentioned is that the win re is privileged because windows stores a decryption key in the TPM that allows win re to decrypt the disk even without the recovery key. That's why the attack requires win re in the first place, rather than booting into an ubuntu live cd or whatever. This also means you don't have to patch all the winRE thumbdrives out there because their secureboot signatures can simply be revoked, meaning they can't pass TPM validation anymore, therefore they won't be able to decrypt any disks.