I think it’s a pretty neat way. Granted I don’t go camping, it’s not my thing, but I also think that you don’t waste a potato, since you dig out the inside, you could use that for mashed potatoes.
So you wasted a potato to cook one egg. That defeats the whole purpose of survival. In a survival situation you could easily slurp the raw egg and have a whole tater.Clean the rock get it hot and fry it if any gets stuck to the rock you can always scrap it up with a knife.