The gold bike is not the same, it is a European mixte frame that has had the upper seat stays and much of the seat tube removed.
As a collectible, the Amflite may yet have its day but it is unlikely that it will ever become a top dollar bicycle like an Aerocycle. It has both “unusual” in the looks department and uncommon in the availability corner going for it but it’s ultimately more Geekin’ than Freakin’.
In the long run, cutting the seat tube will affect the value of the bike in the eyes of collectors who are after factory original bikes but it might also add to the value in the eyes of someone looking for a short, interesting custom.
Unless the bike were to become extremely valuable to the first crowd, any irreversible modifications you make to the bike are not likely to affect it’s dollar value in the market as much as they affect who will be interested in buying it.