A work can't claim copyright on another work.
"Viral licences" aren't.
What they can do is require distribution of a merged work to only be
under their conditions. An image on an article page is an aggregation
of two separate works, the text and picture.
There is a difference between restricting what work your work can be
incorporated in, and claiming copyright. The free art license isn't
saying "if you include this image in your work, then your work is
automatically under our license" it's saying "the only work you can
include this image in is work released under this license" - they are
very different things.
I don't see how the page being an aggregation of two separate works is
relevant - the page as a whole is a work, and the Free Art image has
been incorporated into it.