I initially intended just to put this up as a sort of Rorschach exercise, but people keep asking my thoughts.
I think that Dorsey has got the right solution to the wrong problem.
By algorithmic choice, he seems to be referring to letting people individually choose the algorithms that control the content that they see. (And if I read what is below correctly, he's implicitly saying that his Twitter should have let you leave your feed in chronological mode.)