Would depend on a lot of other factors.
yes, as does mostly everything
The leaner guy will have better carbohydrate tolerance and insulin sensitivity. And if he's routinely dieting and exercising to get to that 10% bodyfat level he's also likely to have depleted glycogen stores and his muscles can hold more glycogen. So when he overeats his muscles just fill up with glycogen without much spill over.
'--basic dieting 101, nothing to do with hormones
the leaner you are the more drastically leptin goes down, so overeating/refeeds can be beneficial to keep it elevated more often. Really the leaner you get the more you need refeeds to keep the metabolism somewhat normal.
Boosting Leptin just boosts the metabolism (if leptin is low). If you're dieting and getting lean leptin will be lower than normal. so you do a refeed or have a cheat day and leptin temporarily goes up for a few days, which temporarily boosts metabolism. Also since you're dieting and training your glycogen stores are probably depleted so a lot of that food you eat during the cheat just goes to refill muscle glycogen stores. And you get a metabolism boosts that lasts for a few days.
Compare that to when you're at 20% body-fat and eating normal everyday and not doing much training. Leptin is already normal so you're not gonna boost it with a cheat day. You're not dieting, not doing much training, so your muscle glycogen stores are already full. So you do a cheat day what are the benefits? You're not gonna get a metabolism boost because metabolism is already normal. Your muscle glycogen stores are already full so there's no place to store all those excess calories except in fat
which, again, goes back to how you get fat
1 by eating fat(fat gets stored as fat)
2 by overeating sugar when you have been overeating for a while(thus have filled glycogen stores) thus sugar, cannot be stored, and made into fat.