I agree with the sentiment with a small caveat, since IMO good writers don't write the way that they talk. The very simple reason is that you can revise your writing but not your talking. But yeah, I completely agree that using an LLM to write your words is intellectual catfishing, and that's a great way to phrase it.

I'm in the process of writing a pretty long essay that has taken a few months. I've written the first draft, and I'm almost done with the second draft, which incurred substantial revisions. At the end of the process, maybe no sentence will be something I would actually utter in person, but the writing is still something I created, and as such, it is a representation of who I am as a person. Had I used an LLM to do any of the writing, that would no longer be the case, and the writing would at best represent me as a person when the LLM is at my side, and at worst (and most likely) not really represent me at all.