I dont think so. It goes on the roof, not much need for aesthetics

This was my best guess. The paperwork mentions attic insulation shield quite a bit but the pics dont match at all what this is. Also it is the cathedral ceiling kit which is literally a sheet metal box that passes clean through the whole penetration through ceiling and roof which completely seals off all insulation from the stove pipe rendering an insulation shield unnecessary. Also the piece in question is too large to fit inside the box so it couldnt even be placed inside the “attic” space inside the cathedral ceiling where insulation would be if that makes sense. My best guess now is that the flashing is ventilated therefore potentially small critters could enter the top of the flashing and get in the ceiling support box and build a nest or whatever and make a fire hazard so perhaps its to prevent that except that the piece when placed over the ceiling support box doesnt completely seal it off which would render it ineffective for that use. Apologies for all the words, it must be quite difficult to picture all this based on text.

You are correct. I emailed the company and this is to seal the top of box if box terminates in the attic…which the instructions emphatically state is not permissable to do, hence all the confusion.