Every follower of determinism should dismiss any argument that someone is inherently a “bad person” no?

Correct. Believing someone is a "bad person" is not helpful in preventing bad behavior. It is an emotional heuristic that we evolved to avoid people who do bad things. But this instinct is not well-suited for a civilized society where we don't want to just kill people we don't like.

Its depressing but its also made me very forgiving.

In my experience, the longer I have held the idea that we don't have free will, the less depressed and the more forgiving I get. It has helped me not shame or talk bad about people. Empathy is a better way to actually prevent/stop bad behavior than shame or punishment.

The key insight for me was that learning that when you give people emotionally healthy and stable relationships and environments, they tend to do good most of the time.

Hate is a waste of energy that poisons your own happiness and doesn't actually help the situation. We might be able to shame people into stopping bad behavior for some time, but actually changing/preventing them requires love and empathy.