First of all, I love your bunny’s name! {{{Kraken}}}
It is extremely important to keep him eating. If a bunny stops eating for 12 hours he can go into GI Statis which can be fatal. You should follow up with your vet and make sure he or she understands the situation.
Some bunnies will never stop eating no matter how sick they are while others stop at the slightest discomfort. So although the abscess was not from his teeth the pain it caused combined with the trauma of the 7 hour car ride, the vet appointment and the removal procedure, not to mention the car rides to and from the vet, would be enough to cause me to stop eating.
If he isn’t eating it is normal that his poops would be smaller and harder but it is a good sign that he is still pooping. If he isn’t eating anything you should immediately start him on some critical care. You can certainly try switching his hay or enticing him to eat with treats like his favorite veggies, bananas or berries. You shouldn’t give him too much fruit but a tablespoon of fruit once a day shouldn’t cause any harm. If he appears to be in pain you can ask his vet for a couple of days worth of mild pain meds for him. This might also help him to start eating again.
When one of my bunnies was sick recently we had to give him meds and critical care. He also hated this and for a solid month he would run away from us if he thought we might pick him up. He has always hated being picked up and this experience only reinforced that instinct. Every bunny will be different but it too Finn at least two months to trust that we weren’t going to try to pick him and force meds on him.
Good luck with Kraken and keep us updated.