When a user access any website of content providers online, they implicitly agree to the terms of service of that provider. When using Peer5, the terms of service includes a language about public IP temporarily visible to other users.
I also doubt it would hold in court. TOS have a very restricted applicability. You can not use them to restrict people's rights in unexpected ways.
Given that they are selling a CDN, and thus likely want to sell to globally operating customers, that might become relevant relatively quickly.