All the horses are dead. quit beating them. He may very well have accepted your input completely, he just cant produce a different looking mask in the time it takes another person to post they all look the same. Give him a few months to knock out a new design, then if you want you can tell him how similar it looks. For now lets all move on, please.
For the record I think the message of similarity has merit and it was recognized, but the more it is said the more it is sullied and the angrier everyone is getting.