Yes Rod deserve lot of credits for this song, but imo I think we shouldn't forgotten that "Thriller" was before Michael influence "Starlight", Temperton during has said during an interview that the music he work for Michael is done with a specific style, a special sound to use for him; who probably couldn't have worked for another artist, the writing is a long process between the writer, the producer and the artist, specially when you work with Michael and Quincy, also if I remember correctly Starlight was a supposed to be the title of the album before the song, simply because Michael liked the name (apparently he have tried to write the song himself, maybe the leak for Captain Eo), so yes it's complicated to give full credits or not to someone, the general public is general didn't care about who wrote a music, I'm not sure they were aware that Michael wrote his own songs to be honest (for example the difference with Jackson five music).
About Elvira amazing news, I would have loved to have her in the music, I wonder how the music video would have changed; Michael should have asked to appear for a version live for the Victory tour.