It's not about doubting him. It's about understanding the interview process and recognizing that 1) less senior employees sometimes don't have all the facts & express inappropriate frustration, and 2) recognizing that someone's interpretation of a conversation is not always what was meant.
I suspect that Tesla management has not shared any info with him that shouldn't have been under NDA. (And honestly, I was a little taken aback over someone sharing anything that they felt was confidential, even though he was not under an NDA, on a public forum. Would you do that?? I'd consider that a betrayal of trust (if true) or just misinterpretation (more likely) of what was said.)