To put it another way, as my pop once told me, if you want to show people that a man who disagrees with you is dead wrong, you don't silence him. You give him a soapbox and invite others to hear him speak, then counter his claims and show how wrong he is.
I think you misread - he doesn't want to ban the movie, merely the entire MGM/UA studio and related companies. A much smaller undertaking than merely 'banning' a movie...