Understanding this may not be addressed by the maintainer, I may have an opportunity to circle back and provide a patch. Basically, right now whether or not the "LoginToboggan logged in block" links to the user account page is determined by a user's access to view user profile pages. However, even if users don't have that permission, they do have access to view their own profile pages. It would be very helpful for LoginToboggan to still support such a link.

The reason it doesn't work right now is because theme_username() has a preprocess function that's responsible for adding the link_path to its variables array. LoginToboggan can bypass that check with something like the following in its theme function:

function theme_lt_loggedinblock($variables) {
  global $user;

  if (!empty($user->uid)) {
    $variables['link_path'] = 'user/' . $user->uid;
  }

  return theme('username', array($variables)) .' | ' . l(t('Log out'), 'user/logout');
}

But again, this is untested and does not constitute a patch. It would need to be seen why the current theme function isn't directly passing $variables through to theme_username(), for starters, and then someone might want to make this behavior configurable in case such a link was truly undesirable.