He didn't "peddle women." Viewers today misunderstand "Mudd's Women" as sex trafficking because they don't remember the historical practice of wiving settlers that it was based on. The program to recruit women to move out to male-dominated Western frontier settlements was the exact opposite of sex trafficking; the goal was to make the communities more wholesome and civilized by encouraging reputable women from Eastern cities to voluntarily migrate to the West, take community-building roles like schoolteachers and seamstresses and the like, and hopefully allow the formation of lasting marital bonds so men wouldn't have to turn to brothels as much.
Certainly Harry's con game was corrupting the intent of a settler-wiving program, but the episode made it clear that Eve, Ruth, and Magda were willing partners in the con. They (or at least Ruth and Magda) were portrayed as golddiggers, women using their sexual wiles to win rich husbands. In that paradigm, it's the husbands who are presumed to be the victims, manipulated by women who pretend to love them but just want their wealth. Perhaps that's another aspect that's hard to recognize given cultural shifts since the 1960s.
And you really can't find con artists charming? I guess there must be a whole genre of fiction you don't like -- The Sting, Ocean's Eleven, the Mission: Impossible TV series, The A-Team, Remington Steele, White Collar, Leverage, etc. Heck, Han Solo and Lando Calrissian are con artists. The Wizard of Oz was a con artist. Angel Martin from The Rockford Files, Booster Gold and John Constantine from DC Comics, Lupin the Third, Quark from DS9, Beckett Mariner from Lower Decks, Vala from Stargate SG-1, Captain Jack from Doctor Who. Heck, the Doctor is a con artist a lot of the time -- psychic paper, false identities, etc.
How are you defining those words? Violence is doing harm. Killing is causing the cessation of life. The definitions are not conditional on the state of mind behind the actions. You're not any less hurt or dead if the person who did it to you felt bad about it.
I know con artists are by nature 'charming', or at least give that facade. I just don't find Harry Mudd charming.
And a lot of those examples you mention, I'm not really into. Except for THE A-TEAM, I never was into any of those shows. Quark, Vala, Mariner, Captain Jack Harkness, The Doctor... those ones, I do like. But all of those examples, including THE A-TEAM, are doing a con to serve a greater good or were selfish and are on a redemption path by using that skill set. (With the exception of Quark, but there are lines even he won't cross.)
There was nothing redemptive about Harry Mudd. So no, I don't find him charming or loveable.
Regarding "MUDD'S WOMEN"... I know that wiving settlers was a thing done in the past, and the reasons for it. Except for Eve, there was nothing wholesome about what they were doing. Ruth and Magda were golddiggers, and Mudd was just as bad. Being the 'charming' conman he was, you really think they went along completely of their own volition? He very likely, given what we know of him, laid the charm on so thick that he likely convinced the women it was their idea. And as you correctly stated, Mudd did corrupt the intent, which is why I call him a flesh peddler.
Regarding M'Benga... again (since you seem to love saying that), he was in a war. He did things he hated. He was traumatized by it. I know you are going by a strict dictionary definition of the term 'violent killer', but let's say someone broke into a home and attacked the homeowner with a gun/knife/whatever. In the ensuing struggle, the homeowner kills the intruder. Are you saying that makes the homeowner a 'violent killer', simply because that person was defending their life? Or how about a woman getting attacked by a rapist, and she ends up killing him with his own knife/gun/whatever in the fight. She's a 'violent killer' because she stopped him from raping and possibly killing her?
So no, I don't think M'Benga is a violent killer.