One of the things Hayek disliked about Social Security was that it gave the government — in this case, the agencies responsible for collecting and dispensing Social Security — a ready-made vehicle for the dissemination of propaganda. Particularly propaganda on behalf of Social Security.

It confers on the organization a power over minds that is in the same class with the powers of a totalitarian state which has the monopoly of the means of supplying information.

As good libertarians, the Koch brothers have naturally read their Hayek. Which is why they do stuff like this.