I agree with your take on this in general: It's better to be tactful and focus on beneficial outcomes rather than "being right".
However, in this specific case, it sounds like:
1. Management was charging a client $60MM for a product they had promised.
2. They were convincingly told that they would be unable to deliver that product.
3. Their response was "Don't let the client find out."
And then what ended up happening was they failed to deliver and still charged the client. That's a massive breach of ethics and potentially outright criminal fraud. Quitting and getting the fuck out of there is 100% the right call.
However, in this specific case, it sounds like:
1. Management was charging a client $60MM for a product they had promised.
2. They were convincingly told that they would be unable to deliver that product.
3. Their response was "Don't let the client find out."
And then what ended up happening was they failed to deliver and still charged the client. That's a massive breach of ethics and potentially outright criminal fraud. Quitting and getting the fuck out of there is 100% the right call.