I’ll give you a hint: NBC has a radio network.
Put yourself in Lorne MIchael’s shoes. Imagine the conversation with your boss if you signed an entertainer who used the network’s precious airtime to call you and your management a bunch of facists.
Maybe that was just a bigger deal in 1977. I remember it and thought it was totally great.
On second thought, you also have to remember this happened at a time before the internet and before cable TV really took off. So the position of ABC/NBC/CBS as media monopolies was a lot stronger than it is today.