This is very typical. He is talking about cutting now former employees access to email, source code repositories, internal systems. It is done all the time. It looks very harsh.
And if I were a customer, I'd be concerned if they didn't cut off access immediately.
IMO it's concerning that they don't have more granular security controls than totally shutting down someone's access (or maybe they do, but they laid off the person who knows how to take access away from production systems without taking away someone's ability to read email)