I agree, I'm also looking for this option where I want to hide my script/expressions from Client having access to Server or from other developers.
If we working on HUB it is not possible to see either based on security rule but if someone is developer then they can export/import the app and load it into QS desktop to see script, which is not really comfortable.
Maybe Qlik Sense should have a security options when the app is exported to folders which can be used in Desktop.
There is no way of protecting your IP from your customers, because they have RootAdmin access to the server, and even if they didn't, they can change the password of the RootAdmin user on the server and get in as you anyway.
Same for desktop, it should support the same functionality (developing in desktop is much faster than in server and running a big reload doesn't bother your users or grind the small dev server to a halt - you can buy a high-memory i7 SSD laptop for the rental price of 1 month of the same size server, so to speak). If export and open in desktop would just show the code, hiding it would be useless.