Yeah, I don't know how QfA came up with the name "palpebral fissure osteotomy" but it appears to me from his description that he simply means moving the lateral orbital rim more lateral with the lateral canthus, and thus more or less horizontally stretching the upper and lower eyelids (laterally). What I see not mentioned however is that the eyeball has a certain horizontal length that you obviously can not change. It may be obvious that this surgery is normally mostly performed on persons with craniofacial syndromes (for example if the eyeball does not have a proper position in the orbital cavity). So if the canthus moves with the lateral orbital rim, your eyeball stays the same length: and the goal of all this is? You risk that the canthus detaches from the eyeball if your eyeball does not have sufficient length to make up for a lateral movement of the canthus + lateral orbital rim (and very likely it has not). Those models you're referring to have a completely different eyeball size and thus their canthi naturally are in a more lateral position. Not everything can be altered, you know.
Multiple studies have confirmed that eyeball size is relatively constant amongst humans - although obviously this may not account for outliers. However factors such as orbital box dimensions, positioning of the orbital box inside the head, development of exterior orbital rim structures, eyelid and canthal positioning, and the positioning of the eyeball within the eye socket together accounts for most of perceived 'eye size'.
For what it's worth, Sinn implied that this procedure isn't necessarily restricted to syndrome patients - he told me it was a feasible procedure with minimal risks. Remember we all thought the lf3 was only reserved for syndrome patients some years back, so let's not jump to conclusions (unless you have some information that we don't - in which case I'd love to hear it).
I wonder why the lateral orbital rim would need to be moved rather than just reattaching the lateral canthus as in a canthoplasty? This makes me thing that there's more to this than just moving the lateral canthus laterally. I've see lateral canthoplasty results where the eye elongated slightly due to repositioning of the lateral canthus - I doubt the feasibility of this procedure if it isn't able to do anything more than a lateral canthoplasty.
Let's assume that the eyeball and internal orbital cavity dimensions remain the same. Even if this was the case, does that mean that an optimal aesthetic result can't be achieved? I mean sure, movement would be limited by the eyeball but Dr Sinn wouldn't advertise the procedure as a palpebral fissure ostetomy (which is what he titled it when he emailed me), nor would he even offer it, if it didn't 'do anything' to the perceived width of the palpebral fissure. Who says that the length of the eyeball is what accounts for the aesthetically pleasing nature of an elongated eye?