If this is all we have to "prove" that Plan 9 was intended for widescreen, then we're obviously back where we started.
I truly don't think Thompson shot a widescreen film.
As to the headroom argument... take the opening shot of the cemetery where the title is printed over. Remember now, this film was meant to have Graverobbers From Outer Space printed over that image. And in that image, in the academy shape, is a carefully placed tombstone/short grave obelisk. Print the image in widescreen and the tombstone is lost and the carefully created narrative environment completely obliterated. Without it, the image is no longer discernably a graveyard. For me, this is the same as chopping off part of a title card.

I've watched all these films millions of times, and without proof from the actual production, this is a major albatross.
