Woody died from Huntingtons and also , I believe, some of his children did as well.
It would seem that Arlo has escaped that fate , Thank God.
As for his support of other musicians rights, maybe Woody thought that it was a higher cause to fight for the rights of humanity. Money was never of great concern to him, and he saw the devil in the face of those in the music industry who wanted to profit from his work. Copyright was just a way for the capitalism that he dispised to control what he did.
Woody marched to his own drum and flatly rejected what many would see as fame.
Go to sleep you weary hobo...........