There is a good article in an old New Yorker about Travers and Disney. You should read that. It is available on line.
Harlan Ellison is not serious or reliable.
I wouldn’t go so far as to say he isn’t serious or unreliable. I do understand Ellison’s perspective. He’s big on writers’ creative control and the issue of intellectual property, and why he was vigorously defending Travers.
You don’t happen to have a link to the New Yorker piece ?
He’s pretty serious! Travers hated the film so much that in the 1990s when the stage musical was being planned she stipulated that no one involved with the film take part.