The issue is really focused on the grammatical function of the word. The researcher is arguing that it's not ever used as an interjection, which "whoa" always is.
I would say the presence of an exclamation mark, in a context where exclamation marks are rare, is strong evidence of use as an interjection. Unless we're arguing that some other mark was mistaken for an exclamation, generally I would say rare typography is "marked" (noteworthy) rather than being likely mistaken. I think the researcher's position is not likely to hold much sway going forward.
I'll note that it's not this decision is not coming from the newspaper article's writer, it's coming from any common transliteration of the manuscript that you'll find. But it's clearly a transliteration decision made because the people doing this assume it is an interjection, and they're using modern punctuation rules accordingly.
> But it's clearly a transliteration decision made because the people doing this assume it is an interjection, and they're using modern punctuation rules accordingly.