I mean, I think that assuming that Twitter's free API tier would always exist in some form would have generally been a safer assumption than many, in that the API is largely of benefit to Twitter (in particular, the novelty bot accounts drive engagement; look at Sam Pepys, or, as mentioned in the article, Pepito the cat), and there's no particularly obvious reason to shut it down entirely; the incentives were aligned.

And people were _largely_ assuming this for non-critical but fun/useful things, like the aforementioned bots, or Threadreader, and so on. So the stakes weren't _that_ high.

We're seeing that assumption fail now, of course, but arguably in a pretty weird difficult-to-predict way.