It is possible to disable the “Reopen windows when logging back in” option, but is it possible to just make it unchecked by default? I have OS X Lion.
Besides completely removing it, as you linked, there is currently no way of unchecking the box by default.
An option to get around this is to use a keyboard shortcut, which completely skips the dialog box, and will shutdown normally. It acts as though you unchecked the box.
Control + Option + Command + Eject
Press all those together.
Maybe it is possible, check out this post with instructions for adding a LoginHook to override restored windows.