Because, at the time, HR 4681 was heralded as _limiting_ the U.S. government's ability to monitor and retain communications of U.S. citizens when, in fact, coupled with omnipresent encryption actually explicitly made it legal to retain such communications indefinitely.

Copying the plain language here:

"... Limitation on retention.–A covered communication shall not be retained in excess of 5 years, unless– ... (iii) the communication is enciphered or reasonably believed to have a secret meaning;"