I'm one of the developers of the webfontloader. I had a quick look and it seems you found a bug. When I implemented the configurable timeout I added it to the core which most modules use. However, you are using the Google module, which uses its own implementation of this particular piece of code and thus doesn't support the configurable timeout. I just fixed this and created a pull request:
https://github.com/typekit/webfontloader/pull/109
This should fix your problem. It will probably take a couple of days for this to be released and to be on the Google CDN. Leave me a message on the pull request if you'd like me to build a temporary build of the webfontloader to use in the meantime.