I'm very sure TAILS can be run on the Pi.
As far as I know there is no build (.iso or SD image) of tails for the Pi or any other non x86 PC architecture machine.
Besides, if you are that paranoid about security and anonymity enough to want to use a system like TAILS you will be wanting to build it from source code. That you have reviewed and checked for back doors, weaknesses and so on.
The source code is here:
All in all it's going to be easier to get Tor working on your Pi and block whatever you have to with firewall rules.
Think about it, instead of carrying a DVD around with which to boot up some computer some where, just take the Pi with you and use that.
Google still not working where you are?
Memory in C++ is a leaky abstraction .