Maybe you should try to explain to your manager why RHEL/CentOS exist and why it's widely used in the corporate world. If he talks about Ubuntu then you could explain to him what Fedora is any why and how it differs from RHEL/CentOS.
I'm not really sure that the reasons for Rhel really exist anymore. The oft quoted Library stabilty is more of a hindrance than a help in modern development environments with well operating CI.
When the dinosaur IBM bought RH it was clear that it had become a fossil.
Of course there is still legacy applications that need that but I see a definite shift away from OS dependant monoliths even in the more traditional enterprises