I refer of course to the Milo Yiannopoulos situation (edit: I said the article didn't mention. I missed the mention.). The man deserved what he got, but there are dozens of accounts that were his "executors" - doing the actual harassment for him in many cases - who got off scot-free, while he remains banned. There is no consistency.
I think there's a possibility that the arbitrary enforcement is partially because Twitter knows that if it were consistent in enforcing its own rules, so much of its population of users would disappear that it would be hobbling itself.
The only "safe" way to use Twitter now is as an echo chamber - only follow people you like, only talk to people who think the same way you do. That's a waste.