Question

This will be a great time saver if implemented.

Answer 1

I rather have an option to Select all muted parts/(note)events, this way you can do more with it than deleting only.

Answer 2

Then how about both? Well, it'd be easy enough to create a macro to delete muted notes after selecting them. I did notice the "Select Muted Events" command. That doesn't apply to muted MIDI notes in the editor, though.