There are good Arguments for Preferring HTTPS, but this website is also available over http to allow it to be linked into the federation. http://matthew.nz 
Wiki client code served from https can only see a small portion of the federation. A good strategy is to use http until every other federated site has been converted to https otherwise you are trapped in the "small internet".
Tip: When doing online banking you want to be confined to the small internet. But federated wiki larger is better. A logged in https server will proxy the large internet but this is not an "open proxy" to be used by just anyone reading an https site. Thread