About disabled items in a listview control

I was trying to emulate something really neat from the Opus filter bar in a script (some of you already tested it): the part that shows extensions and filetype groups, where interacting with a group enables or disables the related extensions. I've gotten this far.

The feature itself works, but I noticed something odd, so I'm asking: when a list item is disabled you can't double-click or right-click it, but you can still interact with its checkbox for some reason (I think this only happens when the checkbox is set to automatic), as shown at the end of the video.

I'm not saying it's a bug (I'm not even sure whether that makes it more or less useful than the filter bar feature), but I'm curious why, when the checkboxes are on automatic, they act independently of the disabled state of their item. Is there a particular reason for that design?

It's rare to mix checkboxes and disabled items, since checkboxes are usually used to let the user enable/disable items within the list, while the disabled item state is typically used when something outside of the list control enables/disables them.

If they are both used at once, you'd normally still want to be able to click the checkbox on a disabled item to re-enable it, I think.