have a listen to the version Nic Jones recorded.
there are some songs that are better unaccompanied[but thats my opinion] but IMO not this one,for example I wouldnt accompany the Factory girl,or Tam Lin,BUT IN MY OPINION this one works well both ways.
its not a question of Murrays abilty ,its a question of personal taste,and what pisses me off are people that go around saying this must be done this way or that.
when the song is sung unaccompanied it is sung differently,not necessarily better but different,it depends on the singer and their abilities.
granted,singing unaccompanied gives the chance to sing more freely,but I have heard some awful turgid unaccompanied versions of this song,with people dragging out the chorus[ala Les Paisley].
Jean Ritchie does a good version on youtube,I have a feeling she used to do it with dulcimer.
I must pm her ,and check if it is my memory playing tricks.