Yes, that is a temporary exemption made by the Librarian of Congress, as the law provides for such temporary exemptions (which can also be renewed by the Librarian -- or not).

Nonetheless, the existence of the DMCA as a legal framework, I think, belies the picture the original comment I was responding to paints, of "Just because there is fair use doesn't mean the content providers need to make it easy to copy their works." The DMCA specifically gives the content providers technological "challenges" the force of law, and makes it illegal to circumvent them, without any general exception for fair uses. There are some few specific exemptions (not a general one for anything that constitutes 'fair use' under copyright law), which are not actually part of the law explicitly, but temporary and at the discretion of the Librarian of Congress.