In this case, the asymmetry appears to be fixed through orthognathic surgery making the overly protruding side smaller - so it can't be an implant. In the after, the mandible is laterally narrower as a whole. What procedures achieved this?
It's the situation I was attempting to describe with one side appearing wider due to the angle of mandible at the jaw corner protruding (therefore the ramus on that side bowed out??), whilst the chin is reasonably central and height of ramus on both sides equal in length.
Eager to hear your thoughts.
Edit: added emphasis and rough diagram
Inability to answer your own question arises from faulty observation and supposition. You start by positing something that might not be correct. But you don't question your own assumption. Instead you just posit it's his jaw angle (gonial angle) that's the cause of his asymmetry and try to describe it by ways the gonial angle isn't looked at.
For example, the gonial angle ('mandibular' angle) is looked at via profile view and if it's BONE you're referring to, the ceph is used. The gonial angle is not assessed from an overhead view nor a frontal view. So descriptions about how 'obtuse' one side is from views it's not evaluated don't go far.
Now because I see that you DO want to THINK about things, instead of giving the (general) answer to what he most likely had done, I'll help you think it through with some hints which should help you figure out what he most likely had done.
1: Question your assumption/supposition that his asymmetry is DUE to--as in caused by-- his jaw/gonial/mandibular angles being different. Ask yourself if he could still have the type of asymmetry he has IF his jaw/gonial angles were the SAME degree measure. Is his asymmetry 'caused' by his jaw angles OR is his jaw angle area looking the way it does the EFFECT of something else.
2: Re-evaluate your observational skills by drawing reference lines to take a closer look at what you might not be seeing without them. I've made this easy by drawing them in for you on the photos you posted. Consider that good observation as to where the asymmetry is coming from will allow you to take a good guess at what he most likely had done.
I hope this helps you (or anyone else) make a good guess and explain the reasoning.
(This exercise open to ALL who wish to answer in addition to the OP.)