You severely overestimate his noteriety.
I agree that he doesn’t have a huge amount of name recognition, but this ousting was a front-page/top-of-website news story so people will likely have heard about it somewhat. I think it’s in the news because of the AI and company drama aspects. It felt like a little more coverage than Bob Iger’s return to Disney got (I’m trying to think of an example of a CEO I’ve heard about who is far from tech).
I think it is accurate to say that most people don’t really know about the CEOs of important/public companies. They probably have heard of Elon/Zuckerberg/Bezos, I can think of a couple of bank CEOs who might come on business/economics news.
I received messages from a physician and a high school teacher in the last 24 hours, asking what I thought about "OpenAI firing Sam Altman".
You underestimate how obsessed people are with chatGPT and AI