I like to feed 20% protein Flock Raiser. The higher protein is better for those that are molting, and helps offset any low protein forage or treats. Plus, the high calcium levels of layer feed can be harmful to roosters and other birds that aren't actively laying.
Layer feed has just the bare minimum protein content needed for egg production. With all the extras, they may not be getting enough protein and have turned to feather eating this rooster to make up the where their diet is lacking.