Every single monster, murderer, bigot etc has a reason for who they are, but we still have to hold them responsible, and in this case promoting their work is absolutely not holding them responsible and its more like most people still don't even believe he did anything wrong. Supporting his work without acknowledging this is fostering apathy.
Holding someone responsible does not mean you need form a visceral or emotional hatred of them as people, such that looking at them or enjoying their work should make you feel guilt or disgust. This would be true for much worse and more clear-cut acts of violence and abuse by those who are clearly mentally disturbed. Even psychopaths, who have the intelligence to know full well that they are doing wrong, did not choose to be psychopaths.
Again, I don't think it needs to be zero-sum, and that we can believe and fully support victims of abuses and other crimes, while trying our best to fully understand and even empathize with perpetrators and criminals, regardless of the extent to which their guilt is proven. We can take revenge and retribution almost entirely out of the picture. And I believe for most of us, that means we can still appreciate the work of artists like MJ in the spirit with which those works were created. Which is to say we can appreciate them in their own right and only remember the abuses so as to not forget the suffering of the victims, and motivate us to better ourselves and our society so as to prevent abuses like this from ever happening in the first place.