Besides the potential issues with sending user requests to this site, it's only a single URL and could be easily ignored. Perhaps I'm misunderstanding something. Wouldn't proxying and caching requests on behalf of your users make more sense?
I believe their site is encouraging users to replicate data from their site on other pages, the data being sourced from multiple locations is intended to be the attack.
Discussion: https://news.ycombinator.com/item?id=46577464