And yet I know there used to be a business (when the Concorde was flying), where they would offer very cheap tickets on the Concorde from New York to London and back, the hitch being that you agreed to take no luggage, and your luggage allowance was taken up by the brokering company, who provided a rush courier service largely for legal/business documents and the like.

I guess this company is slightly different, I think it could be made legal.