Nobody begrudges Twitter the right to (the opportunity to) make money. It's not clear why they decided not to work with the clients. They could have put ads into the API feeds and required that clients not filter them out, or some such thing.

And it's fine that they didn't. It's even fine that they shut down the API. But the lack of communication is ridiculous. Just tell people what the fuck is happening. They don't have to like it, but complete ghosting is the way you burn bridges completely down.