If he has mites they are usually black and look like pepper running around on the skin.
https://the-chicken-chick.com/poultry-lice-and-mites-identification/
I don't think so It really isn't good for much except sprinkling in a feed bag to help keep the feed fresh longer.
There is Poultry dust garden centers or feed stores and Poultry protector both work real good at killing mites.
I don't think he could do this to his throat or neck area. unless he is scratching them out. Have you looked him over for mites? He is certainly a handsome boy. Very sad to hear someone intentionally hurt him. Bless you for rescuing him.