"Now might be a good time to remind everyone that “distinctive phrases” and rare words (high TF-IDF) are not as good for stylometry as subtle differences like “and” vs “the” ratios. If you can easily notice it, someone can easily spoof it."
https://books.google.com/books/about/To_Couple_is_the_Custom...
(obviously, biassed since I'm related)
This doesn't mean "automatically assume the simplest explanation is gospel truth, and if someone suggests otherwise, simply say the magic words 'Occams Razor' to them".
Maybe this occurred. Maybe it didn't. But dismissing it with what's essentially a prepackaged argument adds very little to the conversation.
If I were to leak info, I certainly would try to hide my way of writing. Not sure how to do it effectively. Possibly run it through Google translate and back a few times. Then patch it up to make it readable?
If someone were to do something like this, would it not be in their interest to assume someone else's lexicon or, at least, coopt the lexicon of others in general to throw of the lexicographic 'scent'?
In other words we can't only make the presumption that this is the author(s)' natural language.