Rudi: Polite semantic argument (from the perspective of a US lawyer).

Legal, especially to non-lawyers, sometimes means "not criminal". But breaching a contract is "illegal" even if it isn't criminal.

Having said that, I am curious. Do you mean that under Swiss law there is no ability to enforce the terms of a contract in court? Or do you mean that under Swiss law there has been an affirmative determination that you are not required to adhere to the terms of the contract with airlines relating to awards?