Even though the TNG cast wasn't finalized until 1987, it was announced to be in production in 1986, before Roger C. Carmel passed away. I believe that they already were kicking around script ideas in 1986, probably before the public announcement of the series, and I think the Mudd episode was one of those original story ideas. Of course, when Mr. Carmel passed, the idea was no longer workable, but I believe at least some of it eventually evolved into "The Neutral Zone". I doubt that the Mudd idea ever made it to the script stage, though - more's the pity.