"in this situation"
I am not speaking of "this situation". I'm talking in general. Your overly wordy responses are analogous to someone saying "Someone bought a car, so it's theirs" and you saying "Well, not necessarily, if they decided to lease it out to someone else, or even sell it to someone else, or if they crashed it and the insurance bought it out from them."
The point, again, is that (in general), when an author creates a work, they hold copyright. This copyright allows them to decree who may use the content. A model release from the people in the content is needed for commercial/promotional use.
To calm robbins.photo down, yes, the author could be working for hire. Yes, an agreement with a client could transfer the copyright to them. Yes, any number of things could happen. And yes, copyright allows him to control who "copies" the work. Yes, agreements could have been made usurping that. Yes, the actual usage would be a two step process - 1. allowing the person to use it, 2. the person ensuring they are using it properly. Yes, a release is needed for promotional/commercial use. Yes, releases typically have clauses about prohibiting certain uses. They also tend to have a lot of other clauses. So, to finish, yes, a million things could affect the situation, but IN GENERAL, it is how I described it.