Forum Owner: I Was Hit By Pure Spam But It Should Be User-Generated Spam

So we know Google has penalized sites that accept user generared content, such as Mozilla, BBC and Sprint. They even have a help document on the topic.

One Google Webmaster Help thread has a forum owner asking why his forum received a pure spam notification over a user-generated content spam notification.

This was his question:

we are a file hosting site which focuses on community - people have profiles, they upload content, etc. Due to big traffic, we have a lot of spammers on our site, which we actively fight against, but something always slips through - it's an ongoing fight for years.

Recently I noticed some of our users got deindexed, and rightfully so as they were spammers, but we have been notified that our site is Pure Spam. What I'm wondering about is why were they not categorized as User-Generated Spam. Guidelines for Pure Spam state, that we should fix the content and then make a reconsideration request. Normally we would simply remove those spammy users - should we do that as usual and then make a reconsideration request? Any other ideas?

I find it funny, somewhat, that he is complaining he got one penalty over another. Clearly, Google thinks the site is pure spam, not user generated content spam. I guess one is a lesser evil.

Forum discussion at Google Webmaster Help.