There's "X-Frame-Options: SAMEORIGIN" header preventing the Apps Script from rendering in a page not from sites.google.com (or docs.google.com)
How can I create a python proxy to work from an IFrame. I suspect the proxy needs to replace the SAMEORIGIN tag and work with ajax style POST commands. This is new ground for me, never needed to setup a proxy before.
Example Google Apps Script page: https://docs.google.com/macros/exec?service=AKfycbyrbgVS39Hf-RHYVPbnCKzf_uVaD0sGeFSKEqyRIw
This proxy solutions looks close: How do I get my simple twisted proxy to work?
I found instructions for setting up a proxy on App Engine, but this fails with ajax style POST commands: http://www.labnol.org/internet/setup-proxy-server/12890/
This is a known Google Apps Script issue #546 and #522. About 1 year old with about 100 people looking for a solution.