@redwallhp: Already looked at that. Is not the problem as the installation of the module fills the wp_options table with tweetable_main_menu_permission=edit_themes. So that condition is never matched, anyway.
On Twitter, I got confirmation from other people that this behaviour seems to be general. Perhaps you should make a fresh 2.8.1 install on your own and trace the module’s behaviour in that. I’m pretty sure that it’s a minor glitch and has something to do with the special situation of the module before setup starts.