So, if the customer clicks on the shopping cart link, and the cart is empty, you don't want to tell them that their cart is empty? Instead you just want them to jump directly to the home page without any explanation of why? ... so they can keep clicking on the link and wondering why they're not seeing the shopping cart?
If you don't think that's going to confuse your shoppers then just add this to the end of /includes/modules/pages/shopping_cart/header_php.php to point them to the home page:
Code:
if ($flagHasCartContents == false) {
zen_redirect(zen_href_link(FILENAME_DEFAULT));
}