Submission title mentions NDA but the article also mentions a non disparagement agreement. "You can't give away our trade secrets" is one thing but it sounds like they're being told they can't say anything critical of the company at all.
That's why you can pay $1 to buy a gadget made in some third world country, but you can't pay your employees less than say $8/hour due to minimum wage laws.
Being paid a whole lot of money to not talk about something isn't remotely similar to paying someone a few dollars an hour. It's not morally similar, it's not legally similar and it's not treated similarly by anyone who deals with these matters and has a clue what they are doing.