I think MJ had the advantage in pretty much every aspect here. He was the celebrity with all the fan support. He had all the legal power money can afford. The parents look like money grubbers. The parents don't want a drawn out affair that could make things worse for their child. A lot of victims just want to get through it and move on with their lives. Yes there was no hard proof of guilt, but we know in this world the guilty go free all the time.
Why not? He brutalized and killed countless dogs, making them fight for his entertainment. He still has his life and health, he can do something else that doesn't give him the chance to influence impressionable minds and afford him the chance for other illegal activities.