First, where did you get this from? "Working out is absolutely not a hobby by any definition of the word" It falls within the denotation of the word given it's sense being:
Cambridge dictionary: "An activity that someone does for pleasure when they are not working"
Collins dictionary: "A hobby is an activity that you enjoy doing in your spare time"
Oxford Learners dictionary: "An activity that you do for pleasure when you are not working"
Wiktionary: "An activity that one enjoys doing in one's spare time"
Second is your meaning of hobby is not defined enough, paraphrasing: A hobby is something creative or that develops creative skill. But later on you disagree on videogames that are used to create and express creativity being a hobby.
Your meaning of hobby seems to relate more with if something is manual/physical media than about just relating to creativity or creative skill.
Bibliography
hobby. (2025). Retrieved April 5, 2025, from https://dictionary.cambridge.org/dictionary/english/hobby
Hobby definition and meaning | Collins English Dictionary. (n.d.). Www.collinsdictionary.com. Retrieved April 5, 2025, from https://www.collinsdictionary.com/dictionary/english/hobby
hobby noun - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner’s Dictionary at OxfordLearnersDictionaries.com. (2022). Oxfordlearnersdictionaries.com. Retrieved April 5, 2025, from https://www.oxfordlearnersdictionaries.com/definition/english/hobby
hobby - Wiktionary, the free dictionary. (2025). Wiktionary. Retrieved April 5, 2025, from https://en.m.wiktionary.org/wiki/hobby
Defining sense to understand the sentence meaning is a basic tool of semantics, due to the lack of common cultural referential, if you are that tepid to not understand it there's no point in continuing, disengage. Also don't bend theory to justify your dullnes it's not Marxist