One obvious answer is that Musk/Tesla have way more to lose than a random employee by lying. Any random person can lie about anything with pretty minimal downsi

One obvious answer is that Musk/Tesla have way more to lose than a random employee by lying. Any random person can lie about anything with pretty minimal downsides, even if they're caught red-handed in that lie. A company and its CEO have way more to lose in getting caught in a lie, which puts a slight preference towards believing them in uncorroborated he-said-she-saids like this. Also: "innocent until proven guilty" is a phrase that seems to be eroding away, which is a terrible, terrible thing. The real move here is not to believe either party until you have irrefutable evidence; there is likely some amount of wrongdoing on both sides but none of us are in a position to make judgement calls without that information.