The tiny swiss were the last to delink its currency to gold. They tried really hard, under enormous pressure, but finally relented in 2000 with the new constitution, where the delink was tied to a bunch of other constitutional directives..

So in summary - The country can only do so much before the big guns aimed at it take their pound of flesh.

I am not sure the central bank is faultless in the example you cite, however, appreciate that we live in a world where other powerful people are not interested in the well being of swiss banking customers.