I'm not a client-facing person (a developer) so I might have been tongue in cheek myself as well. Not sure how any of that sounded threatening though...
Christian came off somewhat flippantly and didn’t sound particularly experienced, but overall I trust his account of things. The reddit CEO seems like a weirdo to me.
He 1000% was threatening them. He asked for 10 million dollars to go away quietly, meaning not use his leverage on reddit (who all just took at face value that he's a poor victim). They didn't accept so now he's selectively releasing his secret phone recording and being very aggressive.
He very clearly is being sarcastic, because he knows the 20 million claim is bullshit. He's basically friendly teasing them because if it really WERE that high, then buying Apollo for 10 million might be a good idea, but it isn't and it's all bullshit, so he knew they wouldn't. That's why he says "It's mostly just a joke"