Is Philip Glass still film composer as he did lots of them but even more classical works? Philip Sainton with his only(?) MOBY DICK score would not be a film composer and probably would have not liked tot be called like that.
You could even start to argue if a “songwriter” is actually a “composer” if you start to compare the complexity of a usual song with elaborated classical works.
Usually a “something” composer is used for whose primary focus is on that specific area. Most of today’s composers work in various fields with more or less priority in a field which even may change over time. Didn’t even Goldsmith prefer the term “composer” only although he primarily worked in that field?
I would say any one who work in movies is “also” a film composers. But it must be an actual score and not just a song here and there.