"But the copyright dilemma began in December 1963, when King sued Mister Maestro, Inc., and Twentieth Century Fox Records Company to stop the unauthorized sale of records of the 17-minute oration."
There is a difference in going to court to protect it from being misused and sold without his consent to trying to lock it away so it can be a profit making item.
It is a case of going overboard. Initially they didn't care probably. But then they saw someone making money off it. So they didn't just go and stop that particular instance but went further and made sure nobody would be able to do it. They saw how money could be made from it, and decided they should be the ones profiting from it.
"But the copyright dilemma began in December 1963, when King sued Mister Maestro, Inc., and Twentieth Century Fox Records Company to stop the unauthorized sale of records of the 17-minute oration."