I've come to the conclusion recently that when it comes to separating the art from the artist, individuals must go with what feels most comfortable to them. For most artists, society will not reach a consensus.
MJ's music is tainted for me, in light of the allegations. I can't listen to any of his songs without them coming to mind, so I choose not to. If I worked in a school, I would think twice before using his music in lessons/performances and would err on the side of caution.
Roald Dahl was not only a raging anti-semite but also treated his wife terribly. He amended editions of his works to remove anti semitic references and I grew up with great affection from his stories, so I probably wouldn't deny my children them.
Bowie slept with underage girls, making him a rapist, and yet he seems to be universally loved, even by those same girls. I don't choose to listen to his music either.
Einstein and other incredible scientists often took credit for work their wives produced...
Like others have pointed out, where do you draw the line? I have decided that if a piece of art, whatever the medium, makes me uncomfortable because I cannot separate the artist from their work, I won't engage with it.
I try not to judge others who do still enjoy MJ or Bowie (or...etc) because I recognise that with other artists I can separate them from their art.
But for someone as contentious as MJ, I would probably avoid using his music in schools.