Seems to still be the same issue today May 2020.  I also don't understand why this has not been improved or fixed.

I do have another solution/workaround that seems to do what you want without having to mess with the status of a project.  In the Sales --> Customer tab.  All the client's are listed with a check box next to the name.  Put a check in the box of the client you want to inactive.  Then go to the top of the screen to the drop down button labelled 'Batch Actions' and select 'Make inactive'.  This will then make the client inactive.  Simple enough that you would think Quickbooks would have this same process for when you inactivate the client in the profile.  Is that not all we are asking for?

However for me if you try and inactivate more then one client in the batch action I get an error.  Also seems like another bug since the whole idea of a batch process is to allow you to complete it with multiple clients.

I hope this works for you.