Earlier quoted context omitted.
How would you prevent fraud? Say I have a site that sells Awesome Products. L337Hacker mirrors my site, does a DDOS on the original and lets IPFS take over, redirecting the shopping cart to his own site. Is this a potential scenario? If so, is there any way to prevent it?
All IPFS URLs contain the hash of the content, so you can't change it. There's a mechanism to allow for URLs which can point to varying bits of content, but I'm not aware of a paper which shows its security properties.
If content is created specifically for IPFS-caching (similar to Freenet or Onion), then it may be possible to be authoritative, but content cached from the web should never be considered so.