Never understood the existence of alternative Twitter clients in the first place. From Twitter's point of view, you probably want to have the user experience and ad exposure under as much control as possible, especially when development goes fast like it is at the moment. Apple users should understand that argument more than anyone.
Also feels sort of hypocritical to me to criticize this move on grounds of "openness and transparency" or whatever, but then paying 6 USD a year for proprietary software and promises not to violate your privacy before sending your tweet to a platform that will do whatever it likes with it anyways. For the most part Twitter's API was enabling a bunch of software devs to piggyback on this platform for free. From an economic point of view that makes absolutely no sense.