Do we know whether what we've seen to date is all the footage shot of the scene and whether shooting footage more appropriate for the VFX was ever considered or planned during production? Seems possible that George could have been forced to compromise and go with a different version of the scene than he'd originally wanted due to time, money constraints, then decided in the end to just drop it altogether.
Well, we never see
all the footage, but everything we
have seen from the scene
pre-special-edition is consistent with the edit used in the special edition (along with the human-Jabba being elaborately costumed and performed, something that also is unlikely if he was intended to be replaced with a stop-motion puppet). Maybe there's another version of the scene where there isn't an actor playing Jabba and everyone mimes around where he would be, and they used the one where the actor was present in the end because it was a better performance (or to show off), even if it'd be easier to use the version specifically made to have a creature added after the fact. But wouldn't we have heard about such a cut in the meantime? Would Lucas have described his intention as putting the creature "over the man" rather than "into the scene"?
The way Lucas describes it makes it sound as if his intent was to make put Jabba into Star Wars in 1977 using the methods they did in 1997, tracking the camera, rotoscoping around Han by hand, and painting in parts that are covered up by the human Jabba, not like he wanted to have a puppet-Jabba, then a stop-motion Jabba, then settled for a human Jabba, and finally decided it wasn't worth the trouble and to scrap the scene altogether, which is a more realistic progression (or even that Jabba was just going to be human and was moved off-screen during editing, and Lucas was embellishing the story to make himself seem like more of a filmmaking wizard and visionary).
There's stop-motion in Star Wars, along with matte paintings and any number of other techniques of incorporating VFX into live-action. It's unlikely Lucas wouldn't have known that the only way to put a stop-motion creature into the scene would be to shoot it with a stationary camera and to be very careful about what was passing in front of where he was going to be, and would've just blithely filmed the scene with a costumed actor as a stand-in who was touching everything and assuming that they would fix it in post.
Honestly, though, it baffles me that if in this day and age anyone could see George Lucas as a reliable source regarding his own past intentions and actions. Did you know that the main character of Star Wars is the villain who gets twelve minutes of screentime? It's true!
More to the point, if we have to go through these contortions and revisions to make what Lucas said after the fact even remotely plausible, why believe it at all when a much more plausible interpretation is standing right in front of us, covered in furs?