There are releases that are half soundtrack, half radio broadcast program.  It's not possible to set up a consistent release group for such a release when Soundtrack is a secondary type and Broadcast is a primary type.  (And to be clear, the soundtrack half of the release is the soundtrack for something that is NOT the radio broadcast program on the other half of the release.)

It's also not clear how the Spokenword secondary type plays into this.  Are all Broadcast-primary release groups also supposed to use Spokenword as a secondary type, or is Spokenword something else? Per Broadcast specific types of releases, a radio program that isn't an audio drama is Spokenword.