If none of the tab menu items(either in the main level or in the sub-level) are the current page URL, the tab menu will fail to find any matching items, and then it will by default take the first main item as active (yes I admit it is kind of stupid, but Menucool has to stick to it. It is quite common that a page URL may contain variable queries and hashes, but it is still the same page. So this non-precise matching is often required).
You can create a dummy menu group within the tab menu markup, and style it to be invisible. Make your "excluded" page URLs be included in the group.
1. If you don't need to show the sub-menu bar:
2. Or, if you need to show the sub-menu bar: