There is a "log out" menu item in jessie-based tails
Originally created by @alant on #8364 (Redmine)
GNOME user menu in Debian Jessie based Tails shows a “Log out” item as
of commit e51d6fc (2/12/2014). It should be hidden, e.g. by setting
/org/gnome/desktop/lockdown/disable-log-out
to true
.