xfsm-shutdown-helper sudo error messages

[J. Lewis Muir]

I don't want to allow users to shutdown or reboot the computer when they
log out of their desktop session.

By default, the radio buttons on the logout dialog box are grayed out --
this is the behavior I want. But every time a user logs out I get a
syslog entry from sudo saying "command not allowed" where the command is
a full path to xfsm-shutdown-helper.

So my guess is that Xfce is invoking this command via sudo. I don't want
to add an entry for this to my sudoers file; I don't want to allow users
to shutdown or reboot the computer.

I tried creating the kioskrc file with the following content:

[xfce4-session]
CustomizeSplash=ALL
CustomizeChooser=ALL
CustomizeLogout=ALL
CustomizeCompatibility=NONE
Shutdown=NONE
CustomizeSecurity=NONE

I test to make sure this is working:
# xfce4-kiosk-query xfce4-session Shutdown
MODULE "xfce4-session"
   CAP "Shutdown" = DENIED

Looks right.

I click the logout button on the panel and it pops up the logout dialog
box w/ the appropriate radio buttons grayed out -- same behavior as
before -- this is what I want. But I'm still getting the same syslog 
"command not allowed" errors from sudo as if the logout dialog is 
invoking xfsm-shutdown-helper via sudo no matter what.

I'm running Xfce 4.2.2 on Red Hat Enterprise Linux WS v.3 (x86).

Any suggestions?

Thanks,

-lewis