This means that Bomis' collection copyright would
be violated if
somebody were to copy the website wholesale. If on the other hand the
wiki sources of the articles are downloaded one by one, and a new web
site created out of those, then Bomis' collection copyright won't be
violated. If this new web site doesn't offer the articles under GFDL,
then the individual article authors could sue of course.
There's a little more to it than that: copyrights apply to "creative
expression", and "selection" of what to present is a creative act
specifically recognized (see Feist v. Rural). So it doesn't matter
how they acquire the whole collection, whether they copy the website
whole or download the articles one by one; if they present the same
collection of articles that we do, they have violated our copyright
on that creative choice of which articles to present.
This is similar to a Linux distribution. If you create
distribution, you can claim collection copyright, and somebody
who copies the CDROM image without permission is in violation.
Everybody can however create their own distribution
out of the
exact same free software components that you used, without
violating your collection copyright.
...but that's not true. You /can/ be sued for violating a
collection copyright for publishing the same collection of free
components as someone else, regardless of how you acquired them,
and even if you package them differently. Choice of what to
present is a creative act, and is protected.