If you want to run portaudit against the packages built in your tinderbox host rather than on each individual host here is a small perl wrapper to portaudit.
svn: '/freebsd/!svn/bc/119/tinderbox/portaudit_tinderbuild' path not found (cmd: /usr/bin/svn cat --non-interactive http://svn.tomjudge.com/freebsd/tinderbox/portaudit_tinderbuild)
You need to make sure ports-mgmt/portaudit is installed on your host and its DB file is up to date. You can run it like this:
cd /data/tinderbox/scripts ./portaudit_tinderbuild --build=My-Build