I always thought it was strange that if it was always Georges intention of adding a stop-motion character over the human actor, why then was the actor in full costume and physically interacting with Harrison to the extent that he does, wouldn't it have made more sense from an effects point of view to have Han playing the scene to a guy in a blue suit or filming Han talking to thin air , besides if you look at the only other piece of stop motion character animation in the film the chess board sequence, it's pretty primitive compared to animating a life size figure that interacts on screen with live action elements, I don't think they had the ability at the time to pull it off convincingly.

when you look at the scene itself, it is pretty redundant, there is nothing in the scene that wasn't already explained in the previous Han shooting Greedo scene, I think Lucas cut it from the film because of time constraints, and made up the excuse of wanting to replace the human Jabba (years later) to cover his ass.

If i can remember correctly, the original Jabba from the original comic book adaption, I believe he was a humanoid character that looked a bit like walrusman with whiskers who could've been played quite convincingley by a guy in a rubber mask.