WORKAROUND:
The issue with the XML file is that there is no opening tag, for the closing tag that exists:
</defender_token_audit_data>
So simply create an entry at the top of the file:
<defender_token_audit_data>
E.g:
<?xml-stylesheet type="text/xsl" href="../d5tokenReport.xsl"?>
<defender_token_audit_data>
<date>08 September 2014</date>
<time>(Atlantic Daylight Time) 11:49:14</time>
<timestamp>08 September 2014 11:49</timestamp>
Etc.
Save the file and that will allow you to open it in Excel.
STATUS:
Enhancement request 389122 has been submitted to Development for consideration in a future release
of Defender.