I’m not the person you replied to, but I believe they’re referring to the occupation of “computer”:
https://en.wikipedia.org/wiki/Computer_(occupation)
So yes, at one time all computers were mammals.
The people who write dictionaries generally take a descriptivist approach, that’s why slang terms enter the dictionary after they start to become popular.
The state of the art of human knowledge would be another step ahead of the common use of any language.