I think that having the option to disable the actual clipboard is a good idea: you can prevent an entire class of vulnerabilities (fat-finger-error/human error), which would be extremely useful in security-critical usecases.
For example, when working with financial data or crypto stuff, you have to be really careful to not accidentally copy/paste sensitive data somewhere it doesn’t belong, and you have to manually empty the clipboard all the time (which isn’t foolproof either, considering that doesn’t 100% protect you while you’re working with the data, only when you’re done).
If you know in advance that you’re not gonna use the clipboard in a scenario where clipboard functionality introduces vulnerablities, it makes a lot more sense to have this option instead.
It could be a simple toggle in Klipper settings or the accessibility settings.