It’s embarrassing and shameful behavior by the author, and even more embarrassing that he was willing to share it publicly. If it’s the culture of that startup that this kind of stuff is just typical day-to-day employee interaction, I don’t know who would want to work there, especially given how hot the job market is now.
I’ve had people attack me like that before and it’s not great. It’s always someone in a position of power, too.