Here’s the timeline for posterity:
1. Most popular third-party Twitter apps stop working
2. Twitter says nothing for days
3. Twitter tweets that devs breaking “long-standing” rules have been banned (rules are not mentioned)
4. No one can find the rules being broken
5. Twitter updates its rules to ban third-party apps
As the saying goes, the cruelty is the point.
Twitter could have very easily updated their terms, given developers of these apps plenty of warning, and disabled them after those 30 days. The fact they did it out of the blue and without communication is just being a dick. Of course, they don’t have a communication department to even let people know.