> explicitly saying it was either LLM generated or the person's style was influenced by consuming LLM content

We might disagree here, but if we're strict they did not say "either/or", especially not explicitly. They raised two possibilities, but didn't exclude others.

> there's no reason to believe the style came from LLMs

They say "might" and "plausibly". I think there's no belief there until you assume it.

And even if: It's not unlikely that a contemporary author's mind is influenced by the prevalent LLM style. We are influenced by what we read. This has been happening to everyone for ages, without anyone questioning the agency of writers. There's nothing wrong with suggesting like that could be the case here. It's entirely human.

I know it's easy for one's mind to jump to conclusions, but I am not a fan of taking that as far as accusing someone of "dehumanizing" others. Such an escalation should ideally cause a pause and a think, before pressing submit.