Oh poor Rio :(
Grey's are really empathetic, so all the stress and uncertainty of this year would undoubtedly have rubbed off on him. Not saying it's the cause of the feather butchering, but it could be one of many factors. It could be hormones, stress, diet or illness related.
I can only echo what others have said- if it was Alfie in this situation then the first thing I would do is contact an avian vet to rule out any illnesses/infection.
It's always worth reviewing any changes that have happened in Rio's life/environment recently or around the time his behaviours started changing... no matter how small they may be. Grey's can be quite change adverse.