There are two ways for Kessler to become neutral on offense. One would be to become a 33-35% corner 3pt shooter on decent volume. The other is to become a high level rim finisher that can finish through contact and a 65% + ft shooter. He is pretty far away from both, so then the strategy becomes which is he more likely to develop and focus on that. I disagree that he should focus on both since he needs as much time as possible to develop even one of those skills.
I would think the guy who can finish through contact or at the very least not shy away from contact and hit free throws would be the easier thing to develop. His touch seems so far away from being able to hit 3's consistently, that doesn't seem attainable. I'm not sure how you learn how to embrace contact, but maybe he can take up boxing like Rudy.
On the other hand, maybe being soft isn't something you can coach out of someone and so he really would be better at developing an outside shot.