I think perhaps that if you want to expand on colorful guest characters that have been floating around all over, having it be someone like Mudd makes more sense than an individual nobody in Starfleet has apparently met before Kirk and crew do (unless there's a good reason to keep it secret (classified, or a character with many aliases/have it not generally known, not necessarily intentionally secret).
I also think characters like Mudd, i.e. space criminals with fingers in many pies, are generally more agreeable inclusions than every main character we'll someday meet turning up everywhere for no good reason.
I also think characters like Mudd, i.e. space criminals with fingers in many pies, are generally more agreeable inclusions than every main character we'll someday meet turning up everywhere for no good reason.