Merriam-Webster gives a definition
"vague speculation : a belief without sound basis"
The word's root just means "full of mystery", which is completely appropriate in this context -- describing people who accept the authority of fancy equations as a mystery, instead of delving deeper for a justification from first principles.
It's true that mysticism also has a more specific meaning i.e. describing particular strains of religious or philosophic thought and practice that are tied to the idea of "mystery" in a different way, but I see no reason this meaning should have a monopoly on the word, considering the etymology, see https://www.etymonline.com/word/mystic?ref=etymonline_crossr...
Appeals to authority is not mysticism.
That's like saying it's wrong to use "charismatic" to mean "attractive" because that word needs to be reserved for religious charismatics, or that it's wrong to use the word "agnostic" to mean "noncommital" because that word needs to be reserved for the religious gnostics and agnostics, or that it's wrong to call have "developer evangelists" because that word needs to be reserved for religious evangelicals.