I might be off base here, but if the poster checks bags, WN will know this. Won't they know as well that he did not board? Won't they then verify everyone on the plane and then remove the posters bags as he is not on the plane? IT will delay the flight and really pi$$ everyone off. And it could come back to bite the holder of the Companion pass as well.
IF this were allowed to go through, what a great way to put bombs on a plane.
It isn't going to work. Pay for the damn bags to be sent by UPS or USPS or pay the extra WN bag fees.