That's an interesting question, stingo. It's just possible there's a connection. Manny Greenfield (usually spelt this way though I've also seen Mannie) was doing publicity for Sammy Kaye's band in 1947 and for singer Kay Starr in 1949. Both were big time acts, and I question whether Greenfield would bother taking time to write a column for a comic book. On the other hand he was a music promoter, and the column is about records. Maybe Greenfield took a stab at a syndicated record review column? Or maybe he needed some quick dough and knew someone at St. John.