Nothing is stopping anyone from getting mandibular angle implants except scarring, cost, and surgical fatigue. You'd have to wait a year after your jaw surgery for healing to be complete. Most people have had enough of surgery by that point and just call it quits. There will be more scarring in the area slightly increasing risks.
For my part after I get my revision sarpe, bsso, and lf1 I will possibly consider them. But that is contingent on the jaw surgery going well. It will already be a 1.5 year surgical process.
Surgery is exhausting.