Why put words in other people's mouths? Einstein's relativity relates to frames of reference. Newton was a hardcore Christian, and would never have said that morality is relative. Defend your own opinion using your own logic. No need to appeal to authority.
Don't think linearly about this. What's good for the goose is good for the gander. If these people can jump start their respective fields by delving into an area many thought as wrong morally, why not follow their path with morals and jump start humanity a few hundred years in another direction?
That's not to say forget all of them. Just re-evaluate a few to see if we can find a new frontier.