If he just wants to put the coupe/hatch bumper on the sedan it will work. He needs to modify the mouting holes for the bumper to mount up correctly to the fender. It will have a small gap and fitment issue where the headlight/hood meets and fender.

But if he has the whole coupe/hatch front end and he wants to throw that on. It will also work, but will have a bigger gap where the door and fender meets.

GL.

Here is a picture of how it can look like.