Shut down via Terminal/AppleScript without restoring

Both panic logs indicate the panic happened in the org.openafs.filesystems.afs extension, so that's the logical suspect. The OpenAFS page for Mac OS X seems to indicate that version 1.6.0 is current, and lists separate installs for different versions of OS X. Your panic logs indicate you have 1.6.0fc7, which is presumably a final candidate, not the actual release. I'd disable the extension first, then try installing the current Lion version.

Here's why it doesn't work.

HIDIdleTime is the number of seconds of inactivity, so unless the user do absolutely nothing during fifteen minutes, your script doesn't work.

Here's how to do this in AppleScript.

set timeToQuit to 50700 -- time in seconds =14h05
set currDate to current date

-- do nothing on Saturday and Sunday or this script is launched after 14h05
if weekday of currDate is in {Saturday, Sunday} or (time of currDate) > timeToQuit then return

delay (timeToQuit - (time of currDate)) -- wait 
tell application "System Events" to exists process "Mathematica"
if the result then quit application "Mathematica"