Honestly that wound doesn't look that bad for what they did to him, I too am totally confused as to why they did what they did, and about the way that they did it...ugh. He's a trooper though, that's for sure...
AHBD is completely correct about the raw, unpasteurized honey, it's a natural, strong antimicrobial, and is often used after several Antibiotics are found to be ineffective on a wound, and the raw honey always seems to do the trick. If you're applying it daily, or twice daily, then you should start to see that area around the exposed tissue start to heal within the next day or two. The exposed tissue itself is going to take a while to close, I have no idea what they were thinking leaving that open like that, but I would absolutely stay far away from that particular vet. Hopefully the new vet who is going to do the Skin-Scraping test can take a closer look at the wound to be sure that everything is healing properly.
And honestly I still don't see any signs of Yellow Fungus, if the vet was speaking about the yellow tinted scales that are all around the wounds, well notice how they are ONLY going all around the wounds and no where else at all. That's either a light staining from them swabbing him with Betadine before they removed all of that tissue, as direct Betadine swabbed on the skin/scales lasts forever, or more than likely it simply discolored scales from the wound seepage, and all of that being under that bandage with no air. It still doesn't look at all like Yellow Fungus to me, so that's good. I think he'll be fine, he just needs time to heal, they did a number on him. But he's not
black bearding, so that means he's not feeling too badly.
And you're doing an awesome job, I know looking at that open wound isn't pleasant, but you did a great job cleaning the area out and applying the honey to it, and then wrapping it back up, so you're good to go as far as that goes. Trust me, it's MUCH less stressful for you Dragon to go through that at home than it is to take him back to that vet and have them messing with him. That's another real advantage to doing this yourself at home, the less stress he is under the better off he is...