Hey Team -
Let me explain what's going on here.
First, you create the catalog with product x. Product x gets a static html page created, along with being listed in the index page.
Then, you hide product x.
The catalog runs again, and product x is not linked to the index page. However, product x's static HTML page does not delete... it's just not linked.
So, it is hidden unless someone has a direct link to it.
This will be changing, as instead of overwriting pages, first there will be a deletion of these pages. This will ensure that not only will these hidden products not be linked off the index page, but will simply just not exist as a static product page.