No, it doesn't hold for any desktop application unless you have very good reason to believe that application is the raison d'etre for that computer. If that application is the reason for that computer existing and being used, then maybe you can say unused ram is wasted ram. But if that isn't the case, if your application is auxiliary to the primary purpose of that computer, then "unused ram is wasted ram" is never true for your application.

Photoshop for digital artists or CAD for architects are examples were "unused ram is wasted ram" might be true. Fullscreen computer games are another. But a password manager app? The password manger app is an auxiliary program, not the reason for that computer to exist. The password app should never assume ram not used by the password app is otherwise unused.

There is no such thing as unused RAM after a decent amount of uptime on any mainstream operating system running defaults anymore. If no application has requested it, RAM will get used as file system cache which speeds up the experience in general.