> That's at best a retcon, given given that the RFC was first published in 2008

How so? Apple didn't invent the idea of a secure enclave. Here is a photo of one such device, similar to one I was issued for work back in ~2011: https://webobjects2.cdw.com/is/image/CDW/1732119

No option to get the secret key out. All you can get out is the final TOTP codes. If anything, having an end-user-programmable "secure enclave" is the only thing that has changed.

I think they probably meant "Secure Enclave" in the same way that people say "band-aid" instead of "adhesive bandage", "velcro" instead of "hook and loop fastener", and "yubikey" instead of "hardware security token".