@ericwilson's comment refers to censorship in general, not specifically banning Trump. Plus this piece is just some fun.
Here is a more reasonable example: https://steemit.com/news/@mynameisbrian/martin-shkreli-suspended-from-twitter-following-allegations-of-harassment
I was speaking for myself. You are right, a private company can do what ever it wants, and I can choose to go elsewhere. Twitter (to me) is not worth the memory space on my phone.