Well, I mailed Brett Smith about it and just got his reply:
On Thu, 2010-10-21 at 20:52 +0200, Aggelos Economopoulos wrote:
> > It is not clear if "a general-purpose facility for installing other
> > programs" includes a facility like APT (where you typically download a
> > default list of packages that are available for installation from a
> > remote site). Would such a facility that, among hundreads of packages,
> > included packages of non-free software meet your criteria if it didn't
> > go out of its way to promote the non-free packages?
If the list of packages that is used on the device as shipped includes
nonfree software, then such a facility would not pass muster under the
criteria, no. We definitely had apt and its package repositories in
mind as one common facility when we wrote that section. If the default
repositories include nonfree software, that's "steer[ing] users towards
installation" of the software."
So it seems that your reading is correct after all. I'll ask them to make the wording clearer if possible.