I think this would be useful even if you are diligent with GTD–and I’m not sure that wanting or having this feature really is a GTD failure. A failsafe is never a bad thing. We all get busy; the tools should help us out. I join your request.
Instead of giving them your OmniFocus mail drop address I’d suggest giving them an IFTTT email address or a Zapier one. You can have that forward to OmniFocus with their name prepended to the subject, and have notifications sent to your iPhone when it happens. (And it could forward to OF and you.)
Plus you can also easily disable permissions for a few weeks if you need to ;)