I read this paragraph from Facebook's change's to the platform policy:
You must not incentivize people to use social plugins or to like a Page. This includes offering rewards, or gating apps or app content based on whether or not a person has liked a Page. It remains acceptable to incentivize people to login to your app, checkin at a place or enter a promotion on your app's Page. To ensure quality connections and help businesses reach the people who matter to them, we want people to like Pages because they want to connect and hear from the business, not because of artificial incentives. We believe this update will benefit people and advertisers alike.
Our client wants to add a reward system based on points, each different post shared from their website will give X amount of coins, so you can trade them for products or promotions from their partnerships.
So if I understand correctly, we can't reward users for sharing content from their website using Facebook APIs (in this case Facebook feed dialogue), but what about Twitter?.
Best Answer
That is correct, you are not allowed to reward users for sharing. Users must share something because they really want to, not because they get rewarded for it.
BTW, the feed dialog was deprecated. While it is available again, I recommend using the share dialog.
AFAIK it is allowed on Twitter, at least i did not find anything about that in the terms: https://dev.twitter.com/overview/terms
But keep in mind that those kind of things usually let a lot of users turn away. I highly suggest to tell your customer that it's a very bad idea.