Well since that is the "account" page it makes some sense. The only better place for it may be on the tab itself (replace Log In with Log Out).
I log in with my account, my wife's account, and various other family members accounts, since I manage all the accounts. Therefore I can be on any page on the site when I decide to log out and then log in with a different account.
Therefore, it should be like most other sites (industry standard?) where you can easily log off from anywhere, without straining your eyes or poking around all over the place to find the logout botton.