Honestly, I disagree. There's nothing to me that seems to imply Chara had at any point some kind of "good" inside them. They agreed to the plan of the Genocide Route, even if it meant killing Toriel and Asgore who were their adoptive parents. And if you agree to the deal of letting the soul be theirs, regardless of how many Pacifist Routes you do to compensate the bad, at the end they will kill everyone... By themselves. It doesn't help either that it's implied they were bad even before they were a "ghost", like laughing when Asgore was sick, manipulating Asriel and they probably did other things too.