Board Thread:Support Requests - Getting Technical/@comment-24021506-20131107100250/@comment-366087-20131107121054

The only times this can happen is
 * 1) a wiki is about a children's topic, meaning it is most likely to draw Minors as visitors. Since COPPA regulations prohibit collecting *any* personal information which Anon IP addresses provide, those wikis are restricted to Registered only as a protection for Anon Minors.
 * 2) a wiki feels it should be considered for COPPA compliance and the community agrees, in which case they may submit the reasons for their consensus via Special:Contact.

A brief look at your wiki and I can see the first would not apply. The second would require a highly convincing reason.