Obviously, the amount of apathy and defensiveness displayed by the other employees is a huge red flag that I'm surprised didn't come up in the interview process

Obviously, the amount of apathy and defensiveness displayed by the other employees is a huge red flag that I'm surprised didn't come up in the interview process at all. However: Saying things like "I don't believe you," especially in a public setting, is a great way to come off as a jerk. Once you've decided to call someone a liar, the chance of them getting defensive (and thus poisoning your relationship) increases significantly. You've cornered someone instead of giving them an escape route. Seems like it was a horrible fit on both sides: The author needs a significantly more accountable company, and the company needs someone with a much more delicate touch.