Any question answered...

He does, he sends them the final versions as what he would use for himself, but some models seem to want to add their own takes on the matter...

I say let 'em! from experience, clients post work almost always turns the photos into a clusterfuck. Why ask a professional to do it in the first place if you're gonna do nothing but botch it up later?!
Good luck to your friend, image copyright is a bit of a prickly one.