[graeme]

Entirely possible the rss failed validation triggered some spam flag that isn't documented, because documenting anti-spam rules lets spammers break the rules.

The amount of spam has increased enormously and I have no doubt there are a number of such anti-spam flags and a number of false positive casualties along the way.

[Eisenstein]

If failing to validate a page because it is pointing to an RSS feed triggers a spam flag and de-indexes all of the rest of the pages, that seems important to fix. By losing legit content because of such an error they are lowering the legit:spam ratio thus causing more harm than a spam page being indexed. It might not appear so bad for one instance, but it is indicative of a larger problem.