Disable Shift Cmd Q for logout
The following works for me on 10.9.5:


System Preferences > Keyboard > Shortcuts > App Shortcuts.
'+' to add a shortcut
Application: All Applications
Menu Title: Log Out [Your Name]…  Here, copy the exact text shown in the Apple menu, replacing [Your Name], and note that the ellipsis … must be typed with alt-;
Keyboard Shortcut: ctrl-shift-cmd-Q (or whatever you prefer: something different to shift-cmd-Q)
Log out and in again.
Note that the keyboard shortcut has changed in the Apple menu, and shift-cmd-Q no longer triggers the menu.