This artist only does painted-over-AI art and AI can already generated time-lapses. Feel free to read topic #22285 is this is news to you.
What do you mean by AI can generate time lapses, that sounds like some jibberish to me, an AI researcher, with all the fine line art and intricate rendering. Painted over how? I was investigating this artist, and asked them for raw footage of themselves drawing their next piece within clip studio and their pc, and there seems to be no drawn over element? I can't fully deny the possibility of tracing an AI art, but how in the world are you really supposed to refute that, Perhaps they have used AI for some things in the past but this one is relatively clean, I say we give them the benefit of the doubt considering how cooperative he is, with providing evidence that disproves using AI. I've ran it through some tests myself. Your words are circumstantial evidence (art style looks like AI) and have no weight here.
In any case, I am curious but what do you really need from him to prove a piece of his is completely AI free, I'm aware he's been put under more scrutiny having used AI assets in the past, but asking them to change their style is pretty rough since it's more or less consistent.