Perhaps the knowledge that someone with the means and motivation to perpetrate a $170K fraud like this also has the means and motivation to pay $15-20K to have you harmed or killed.

http://en.wikipedia.org/wiki/Contract_killing

"Make it look like an accident."

Actually, that's a risk even if you plan to abide by the NDA.

For what it's worth, I think this offer is an entertaining troll and not actually real.