This isn’t exposing some unknown flaw. As the article says, this only applies for people who willingly use Bitlocker Recovery, which stores your key with Microsoft.

Those concerned about privacy would never do such a thing. As the article also states, the majority of FBI requests cannot be fulfilled because the accounts didn’t share their keys.

…20 requests for BitLocker keys per year and in many cases, the user has not stored their key in the cloud making it impossible for Microsoft to assist.