May be that your local A.M. station chose not to play it, and the Friends of Distinction version made the Masakela version instantly obsolete for golden oldies formats. I didn't hear "Eve of Destruction" until a few years later, as my family lived in Alabama in 1965, and it seemingly got banned there, likely for the line "You talk of all the hate there is in red China, but turn around and look at Selma, Alabama". Not that it wasn't true...
Agreed in retrospect, had no knowledge of him at the time apart from the song. That scenario actually seems to perfectly fit the criteria TTK set in the first post. As far as Jankowski in the USA, that cut is the only time he was ever on the radar of much of anyone in the USA pop or jazz worlds.