I think they could have said something and I think most people would have understood the change. BUT, coming from a person that didn't even consider this bumper until recently, I still think it'll look good. Mind you, I never had my heart set on a true-as-can-be replica of the RS bumper so take that with a grain of salt.
F2 made a replica of the RS bumper and made their own changes.
ED made a replica of the F2 bumper and make their own changes (by accident I guess).