Ther are plenty of songs about murder and revenge, even before you go into folk songs:
I shot the sherrif
Bad like Jesse James
Hey joe,
Folsom Prison Blues.
Delilah
etc etc etc.
I don't think any of those are actually glorifying or condoning murder. They are simply telling a story.
IMHO making a big fuss about some song lyrics just detracts from the real issues in the world.