The EU has unlimited ability to punish Switzerland with extreme precision and at a low cost, Switzerland has no meaningful ability to go tit-for-tat even at a very low level.
> At any rate, there's nothing about being an island that automatically stops a crazy genocidal EU trying to starve another country. If I recall history correctly, less than 100 years ago a big European country was attempting to starve Britain to death by systematically sinking its cargo convoys. Then just a few decades later east Germany was trying to starve Berlin by shutting down rail links. Note: both attempts failed.
Yes, you’ve succeeded at explaining why it makes a difference that Britain is an island. At the very extreme end, the EU would actually have to go to war with them instead of just issuing a NOTAM and sending a few cop cars to monitor border crossings.
Also, FWIW, at no point during Brexit has Switzerland been a better partner for the EU than the UK has.