Adding a gay character to a Disney movie or a bunch of black characters in odd places does not increase the audience. Disney knows that gay and black audiences will not rush out to see the movie. The purpose of these two additions to the movie is for the critics. Disney wants to get past the lily white conservative branding. So they can be accepted in California public schools and have the New York Times give a more favorable rating. Disney knows their bread and butter are the young white girls and their mothers looking for some predictable teenage no core (not hard core, not even soft core) romance.
I think you nailed it.