NDAs do not cover criminal offenses, you cannot NDA your way out of that. If you try to make an NDA saying no one can talk about your sexting with a minor it doesn't matter who signs or what the NDA is, its a potential criminal case and in fact its a crime to try and shield a crime behind an NDA.
What an NDA can cover is civil cases aka settlements, so if Doc did something illegal but settled with a third party and paid them millions to agree not to sue then there can be an NDA to cover not disclosing the settlement in any way (the money settled the case). It still wouldn't cover the actual crime itself though, anyone can blab about that anytime they want as long if they have actual evidence, but no prosecutor would prosecute if the victim says they will not testify as they have settled out of court for money.
reading between the lines thats probably what happened and amazon bitched out, shoulda just said we banned Doc for sexting with a minor, maybe they got the evidence in an illegal way (spying) or most likely amazon legal was worried they'd catch a lot of bad PR for basically being a pedo platform so tried to keep everything out of the public eye, which is stupid since stuff like this always comes out.