I respectfully disagree. As I have stated a number of times, I believe this could have been a postmortem attempt to stop the fluids that would have been issuing from the nose and mouth. Which would have been more than a trivial act to accomplish. I don't think it is safe to assume the tape was placed either antemortem or perimortem. My disclaimer here is that either of us could be right, but that would also be my point.
You can state it all you want, as can the dream team, but if I was on the jury, I wouldn't buy your theory for one second. Duct tape doesn't stick to wet things, and why on earth would you duct tape the mouth and not the other orifaces. Makes no sense at all.