So tell me which part of this statement (true or not) deserved for him to be publicly drawn and quartered by somebody in a significantly more powerful position than him?

Officially: no reason. And I get this; I vaguely know how CA employment law works and that you limit your liability by not stating a reason. It's also really hard to work through in your mind. The best theory I have is that, two weeks earlier, I raised concerns about donating 10% of ad revenue to charity. Some management likes getting feedback, some doesn't. The reason I had concerns was that this was revenue, not income. That means you need ~10% margins to break even. This can be hard to do; Yahoo and Twitter don't. Salesforce does something similar, but it's more all-around, and in a way that promotes the product without risking the company's financials.

It's far more likely that this is the first time he's ever been given clear reasons for why he was fired. I've never been fired, but when other employees I've known have been fired they've never been given reasons this clear. It's always a variant of "it just wasn't working out." This can lead to very genuine confusion, and so I think it's really jumping the gun to assume that he was deliberately lying about the situation.

Artfully telling lies is really a managerial skill in many workplaces.

where are the proofs that ex-employee is lying? It can be CEO is covering up. Is it not?