If the CC doesn't prohibit it then why is it my fault for earning it? What if I didn't even intend to earn the points? The fault lies solely with issuer of the points.
This is why the Nordstrom bros story is so shocking. All they did was make online orders through a portal. Nordstrom cancelled them and paid out the cashback site. That the brothers got jail time for that, when all they actually did was submit online orders, is very surprising.
I'm no expert but I'd like to believe that a better lawyer could've won that case.