Why would this excuse the portrayal of witchraft or wizardry in a positive light?
In reality, witchcraft is an abomination. The protagonist practices "witchcraft" or "wizardry," and sets a poor example for children.
In reality, witchcraft doesn't exist.
Because in the FANTASY world of Harry Potter there's no matter of choice, making all wizards evil in HP is like making all blue eyed people evil.
HP isn't reality, has nothing to do with reality, has no resemblance to the world of witchcraft the Bible warns against, does not send people on an occult path, and does not open a gateway for Satan. It's just a series of fantasy books that present a made up world and until you realize that you will continue to drive fandom away from the faith with your closed minded factless ravings.