I was reading through this question Can a Muggle do anything with a wand? and Valorum’s answer said this:

JKR addressed this point in an interview in 2006;

"I been asked what would happen if a Muggle picked up a magic wand in my world. And the answer would probably be something accidental... possibly quite violent. Because a wand, in my world, is merely a vehicle — a vessel for what lies inside the person."

So then, what if you’re someone who is completely good and has no "violence" inside of you, would you then be able to use a wand?

No, you've misunderstood the quote.

JKR isn't saying that the result would be violent because violence is what lies inside a Muggle (though it does sound like something the Malfoys might come up with) but that the result of a Muggle using a wand would be uncontrolled because the Muggle lacks the ability to control magic - that's the power that lies inside a wizard, and which the wand is a vessel for.

By way of analogy, imagine a three-year-old driving a car. The outcome would probably be unintentional, and possibly quite violent, but that's not because it is in the nature of children to be violent but because they lack the ability to control the vehicle. Their character doesn't matter, only their ability.

No, Muggles can’t use wands.

Muggles can’t use wands, whatever their moral alignment or personal feelings towards violence. As Dumbledore explains in his notes on “Babbitty Rabbitty and the Cackling Stump”, the violent reaction comes from within the wand itself, as wands can hold residual power that may be discharged from the wand.

“While the “rogue” ability to perform magic sometimes appears in those of apparent non-magical descent (though several later studies have suggested that there will have been a witch or wizard somewhere on the family tree), Muggles cannot perform magic. The best — or worst — they could hope for are random and uncontrollable effects generated by a genuine magical wand, which, as an instrument through which magic is supposed to be channeled, sometimes holds residual power, which it may discharge at odd moments — see also the notes on wandlore for “The Tale of the Three Brothers.”
_{^{- The Tales of Beedle the Bard}}

The reaction that a wand can have when being waved by a Muggle has nothing to do with the “goodness” of the Muggle waving it. It’s simply the magic stored inside the wand being released when the Muggle (who can’t do magic) tries to use it.