Why would the EU be so irrationally butt hurt about it? It seems easy enough to let the Swiss have their policy and both continue to benefit
Edit: EU can void all the other contracts, but why would it want to? Why do they care so much about how many immigrants Switzerland has?
Swiss can have their policy, who said they can't have it? It's just that they can't make EU have the Swiss policy. If Switzerland wants to be a 3rd party country, they can do that and negotiate visa regime, import/export controls etc with EU like everyone else who is not part of EU or don't have a deal. They can be like UK or Turkey for example, or be have entirely different relationship.