OK Well I've found that the library files are absolutely riddled with unreasonable dependencies on software serial. Even though there needn't be.
I suspect that, like the Arduino process, Adafruit accepts libraries from less-than-professional programmers. I find it difficult to believe that, as good as their products and libraries usually are, that they developed this library that way.
It was nice of you to investigate, and develop a fix. How are you removing the dependency? By having the user provide the soft or hard serial instance to use?