No. Just no. Styles make fights. Him beating DC at LHW says nothing about how well he would do against HW's. DC beat guys bigger than him by being much faster and much more technical. Jon isn't fast, athletic or technical enough to overcome big size and strenght discrepencies. Jon highly benefits from being much longer than everyone he fights. The toughest match he had was against a guy that wasn't much smaller than him. The HW division is full of those guys. Plus, stronger, heavier and more powerful.
At HW Jon wouldn't have the main advantage that made him so dominant. His opponents wouldn't have over 10 inch disadvantages over him. They would be much closer to his frame, mostly heavier and naturally stronger with a lot more power.
Nobody knows Jon better than Jon himself. If he actually believed he could be the HW champion, why would he be fighting LHW's? Let's be serious here. Do you honestly believe that, given the opportunity to choose, ANYONE in the world would prefer to be known as the LHW champ instead of the HW champ?
Jon would only gain by being the HW champ, or even two division champ. More money, more fame, more respect. If he hasn't made that move yet is because he doesn't believe in himself.
Do you honestly believe that if Jon was facing guys his height and closer to his reach on a regular basis he would be undefeated? Jon is not a technical fighter in the traditional sense. Nor is he particularly fast or powerful. Most of what he does works because of how long he is. Yes, he knows how to use his reach, but still, there are a lot of technical flaws in what he does. Those flaws are forgiven by the huge physical advantage he has.