Thank you for your thoughts Kavan !
I have more to say but time's short and I'm in the middle of writing a paper for university. I'll come back to your comment when I'm done with my essay.
In the event I'm not around, I'll provide some more info that could explain why the guy hesitates to offer surgery. I'll also provide a diagram having to do with rotations.
1: The angle of inclination the lower incisor has with the border of the mandible looks to exceed 95 degrees. It's not uncommon for prior ortho to get 'bite rite' by flaring out the upper and lower incisors which might contribute to the lip 'stick out'. I don't remember the exact angle but just to say the maxfax docs like it to be near range of 90 to 95 degrees and not overly obtuse. So, maybe he doesn't want to pluck a pre-molar which would be needed to get the lower incisor with in the range of inclination they like it to have when doing an advancement.
2: Although the lip 'stickout' is made less and re-orients to rotate down and backward with CW-r, lack of tooth show along with complaint of lower face too short would require an OVERALL down graft (one to the entire maxilla) with net CW-r. Thing is that an overall down graft to ELONGATE the maxilla is not something all surgeons do (advanced skill set is needed). Just sayin' for short lower '1/3rd' and lack of upper tooth show, a down graft that spans the entire maxilla is needed. So, you would have to establish if he actually does them. By the way, an overall maxillary downgraft to increase the height of lower face can have net CW-R, net CCW-r or 0 net rotation if length of it is uniform throughout span of maxilla. When the front of it is longer than the back of it, it's net CW-r and when the back of it is longer than the front, it's net CCW-r. But no matter the rotation, what the grafts have in common is LENGTH added to lower 3rd of face. Monkey muzzle (chimp lip) has more to do advancing over an unfavorable rotation when they advance both the jaw and maxilla equally where they have to advance the maxilla TOO MUCH to because they DON'T do a CCW-r in a person who could need that in order to have the mandible advanced more than the maxilla. So, it's more of a matter of an equal advancement of both jaws in people who start with an unfavorable inherent rotation of the jaws which is not changed (via rotation) before hand. So, chimp lip is neither directly associated with CW-r or CCW-r pe se. It's directly associated with MORE advancement of the maxilla than a person might need when a doctor advances both jaws equally (linear advancement) to get a large mandible advancement and the maxilla goes along with the same ride.
3: Another thing that needs a graft of sorts is a genio that goes in the direction of downward and outward. It makes a bone GAP than needs to be filled in with a graft. So, maybe he doesn't do the type of grafts other docs do
4: Depending on how much you conveyed to the doctor that your bone structure was not as 'robust' as you would like,maybe he thought you were expecting too much from maxfax surgery. Bimax/double jaw surgery will do nothing for cheek bones. Although they can vertically elongate the maxilla for a longer lower 'third' of the face, they can't make the jaw bone itself more robust. That is to say, it doesn't actually make a vertically short mandibular body longer or more 'hefty'.
All that said, I think it could be a combination of your expecting to get a more 'robust' bone structure from maxfax surgery and also, possibility of pre-molar removal and also a question of whether or not he performs the type of BONE GRAFTING techniques associated with maxilla elongation and also a type of genio that goes down and outward also needing bone grafting. Like it sounds more in that direction than in direction of getting 'chimp lip'. I'm not predicting whether you could or could not get chimp lip. Just saying, I don't think that possibility is the salient reason for his being disinclined to encourage surgery.