This is so dumb. If a business wants it's latest idea/product to be kept on the down low then you should just respect that. Don't get all high and mighty about it. A business is entitled to keeping its projects under wraps, its how they stay ahead of their competition. Otherwise other companies can just come in, develop their own version and even beat the other company to the punch. Imagine if video game studios had their projects leaked from day 1, or a big tech company. They'd find themselves surrounded by competing products as soon as they launch, if not before.
Sign the damn NDA, it's doing you no harm, and if it is, don't sign it and don't take your employer's money. (and grow up)