From the source code: http://www.focusontheuser.org/dontbeevil/script.js

if (/MSIE (\d+\.\d+);/.test(navigator.userAgent)) { alert( "Unfortunately, this tool does not currently work in Internet Explorer. " + "Please try another browser such as Firefox, Chrome, or Safari."); return; }

That's not very nice. Surely this can be made to work for at least IE9 :)