Bert, must have given considerable thought to what he did.
I see it as an extension of the philosophy the end justifies the means,which is the philosophy of communists and also the ruling classes of the capatilist system.
the two just have different ends.
Bert presumably[and Ithink he was right]considered his own songs and his alterations a bonus to the tradition .,he clearly wanted his songs to be part of the tradition,and at the time he composed them,perhaps he thought ,they wouldnt be judged on their merit if he announced them as self compositions.
was the attitude to modern songs perhaps different at this time.?
one person who may be able to throw light on Berts reasons,would be Jim Carroll.