Don't need a better chin, he needs a better defense to protect his chin. Punch resistance or lack of is like any other god given ability you either have it or you don't. Can you work on it, yes, but chances are it won't improve much. In my opinion, that's the one area in boxing that is hard to improve, you can improve speed, power, defense and most other physical attributes related to boxing, but punch resistance is something that I don't think you can improve on.
he would still be beaten, by nearly flawless. I mean the dude can punch, has speed and well his technic might be room for more...