> a technological measure “effectively controls access to a work” if the measure, in the ordinary course of its operation, requires the application of information, or a process or a treatment, with the authority of the copyright owner, to gain access to the work.

DeDRM tools are obviously not the ordinary course of operation for the DRM system chosen by the copyright owner, and using (for a different purpose than intended) a decryption key that the copyright owner has taken deliberate steps to hide from the consumer stretches any notion of "with the authority of the copyright owner". Copyright licenses usually come with strings attached, especially with regards to what kinds of uses are being authorized.