That's actually an RSS 2.0 feed, not Atom.
Anyway, the problem is that it doesn't contain link elements and the guid elements do not have the isPermaLink attribute set.
I guess this is one case where Geeklog's feed parser could be more tolerant: If we don't have a link element but we do have a guid, then use the guid even if it's not marked as a permalink. Need to check with the specs first, though.
Can you please submit a feature request for this?
As a workaround, open system/classes/syndication/rss.feed.class.php and search for this piece of code: