Having /includes/ under document root - and trying to fix this via a robots.txt entry (??) - wouldn't reflect well on Obama, if they actually had any meaning :)
Sorry, I'm taking that back... I was thinking of Obama's campaign site where you could actually access stuff like /includes/footer.php (at least for a while, seems to be fixed now)
You're making assumptions about what that directory is for. Perhaps it is used to store static HTML pages that are included from IFRAMEs on other pages.