"I wonder if a link flagged by the disavow tool and confirmed by the user weaken the Google juice of the source site." We haven't been using disavowed links as

"I wonder if a link flagged by the disavow tool and confirmed by the user weaken the Google juice of the source site." We haven't been using disavowed links as a reason not to trust a source site. So it wouldn't weaken the Google juice of the author's/source site if the company that sent the email had just disavowed the link.