I did not recommend it either,the point is that,
a folksinger by having listened a lot,has unconsciously absorbed other peoples styles,your grand father was not an island unto himself,he must have heard other singers,and without thinking[UNCONSCIOUSLY] about it absorbed style.
this is why Kentucky banjo players sounded different to Texas,Donegal fiddlers different to Kerry.
your remark about collectors is silly,if you knew anything about Jim Carroll,or heard any of the programmes of his collected singers,you would know he was too sensitive/sympathetic to say anything,as stupid as that.
youare also clouding issues by introducing traditional singers[and their environment; your grandfather]with the original poster who almost certainly is in a revival situation.