Mhaura, theoretically Tails could be rooted. An attacker who roots Tails can disable the firewall and bypass Tor. This guide protects against that because Tor runs outside of the VM. The chances are slim of that happening, but that's the worst case scenario. A more practical approach is that you might not like Tails. In this setup (as well as my Whonix-Gateway guide), you can make any OS the workstation and isolate it behind Tor.