Earlier quoted context omitted.
But there is no need for Twitter to allow you to do that for free just because. From a pure business perspective it's either Twitter dies or Elon pays the bills.
From a business perspective, you don't want to alienate developers who work to build your ecosystem. A more sane way to do this would have been with a public tweet explaining why they were doing it (ad revenue), a 3 month lead time, and an API for helping apps get users to "upgrade" their account.
Frankly, I don't think Musk much cares for the developers. From a business perspective, he might be right here - developers aren't the ones watching ads or paying for microtransactions, users are. The developers, at his scale, are a liability. Restricting their capabilities and profiting from their struggle is just part of the modern tech stack. I hate it as much as you do, but calling it "insane" is a hysterical double-standard that crops up just too often on HN.