Let's say we have a linked PDF which is set to "Passthrough". Then we turn this PDF as embedded and leave it as "Passthrough". At this point the button "Edit Document" should not appear IMO. The button should only appear if we set the option to "Interpret".
In my case preflight warns about a missing "Lucida Grande". After embedding the PDF preflight is still reporting only 1 font missing. As soon as I edit the document, there are "Lucida Grande" and "HelveticaNeue-Bold" reported as missing.