I think we're entering a gray area here, as haki is/was a perfectly normal word before Oda attached the mystic energy label to it. Of course, that's not going to stop anyone from looking up every instance where the word was used and branding it with the Haki label no matter how innocuous the usage.
Now, if you want my personal take on all of this, I look at how long it took for Haki to actually be associated with the mystic energy context and conclude that Oda wrote the idea in after the series was already well underway, and that Shanks's act in scaring away the Sea King was nothing more than what people do in real life to frighten off pets and small animals: look threatening and project an aura (not in the literal sense) of hostility.