That seems quite implausible. Not that the managers there weren’t jerks, or that this didn’t contribute to the conflict, but there seems to be a lack of reflection on this story because there is almost certainly more to it than that.
I was simultaneously doing conference marketing and managing our infrastructure. Dad died, I told them I had to go, didn't communicate much, because my dad had died, and they thought it was inappropriate that I wasn't calling them while taking care of my mother.
I also found out later that a certain YCombinator partner found out that I had 2% of the company and suggested they fire me before I vest because it was an "obscene" amount of stock for a single employee to have, even if I was the 7th employee and took a 50% salary cut in exchange for that stock.
So yeah, there's more to the story.
Most of the US has at-will employment, and they can terminate you at any time for any legal reason, and there's no federal-level laws on offering bereavement time off, so I bet this happens more often than you think (at least a cursory google search brings up quite a few people telling stories of it happening to them).