Why does Merged supplier site show up in 'Acive' search?

We do merge supplier sites and obseved that the "Inactive Date" field on those sites became disabled after the merge. So far so good; and as per the documentation.

The confusion starts when this very site that was merged; appears in search for "Active" supplier sites on the quick update tab.

In the 'Manage Sites', not only it appears but also is updatable for all other fields (e.g.: options like Primary Pay, Purchasing etc.) except "Inactive Date" which is disabled.

Is this intended? if yes, why and how is it desirable to update "inactive site"?