The ebuilds already have RESTRICT="mirror" but "bindist" should go along with it: If the distfile cannot be redistributed, then the binpkg cannot be distributed either.
I am currently investigating why firefox-bin has RESTRICT=mirror at all. We will probably get rid of that restriction...
(In reply to Ulrich Müller from comment #0) > The ebuilds already have RESTRICT="mirror" but "bindist" should go along > with it: If the distfile cannot be redistributed, then the binpkg cannot be > distributed either. This has changed, RESTRICT=mirror is gone. Therefore RESTRICT=bindist is also not needed... It was added in the past to allow upstream to track download stats. But this is not needed anymore so...