According to Postcom: “We’re shocked! Shocked, we tell you. The Postal Service has opposed any intervention by any of the parties who were going to be tagged with higher rates as a result of its exigency request. Perhaps we’ll need to wait until after December 3rd for the Postal Service to come back to its senses.”

USPS filed a motion in opposition of 11 Mailer groups intervening in rate case appeal:

Pursuant to Federal Rules of Appellate Procedure 27(a)(3)(A) and 27(a)(2), Petitioner United States Postal Service hereby opposes the separate Motions to
Intervene filed by the Newspaper Association of America, Time Warner Inc., Valassis Direct Mail, Inc., the Affordable Mail Alliance, the Alliance of Nonprofit
Mailers, the Association for Postal Commerce, the Direct Marketing Association, Inc., the Magazine Publishers of America, Inc, the National Postal Policy Council, American Business Media, and the National Newspaper Association.

These eleven would-be intervenors were not “parties” below; they were merely commenters. Accordingly, they are not entitled to intervene as of right. Further,
allowing a host of mere commenters to intervene permissively in this review proceeding would unduly burden the original parties and this Court, interfering
with the Court’s ability to resolve this petition with the expeditiousness the Court has already recognized is needed. Therefore, the motions should be
denied.

Allowing mere commenters like the movants to intervene as parties could cause practical problems and needlessly delay and complicate adjudication of
this petition for review. The would-be intervenors have made no showing that their interest in having lower postage prices is any different from that of dozens
of others who filed comments with the PRC — or hundreds of millions of others who use the U.S. Mail. Allowing entities with such a generalized interest to
participate as parties would likely result in undue delay and distraction.

source: see Postcom.org for complete document