How can I politely say "no way" while still getting the job?
Don't go into reasons, or get into a philosophical debate about it. The only time I've given an explanation was for a volunteer gig where I refused to sign an NDA at all, and had to explain to the coordinator "We can either be employee and employer where you pay me a lot more money then you have, or we can be two buddies working on a thing for free. We can't be two buddies where one guy has a contract against everyone else."