I think the real reason Colonel Tom would not allow Elvis to do A Star is Born is that he did not want his "boy" to be exposed to the business side of showbiz with Streisand. His worst nightmare was Elvis and Babs talking together during a break in filming and Babs telling him that as he was the King, he really should not have the old Colonel anymore as his manager. Babs- "You're Elvis Presley, the King! You don't need the Colonel anymore!"
he really did ruin Elvis big time.. to bad no one had the power to get him away from ElvisFrom what I read about the Colonel, every time a promoter from the UK, Australia, or Japan had a very high and generous offer for Elvis to perform overseas, the Colonel's answer was always "That'll be fine with me but how much are you gonna pay my boy?".
interesting reading it nowI had an idea on this a few years ago:
https://www.alternatehistory.com/forum/threads/what-if-elvis-had-lived.156934/#post-4358603