Could be but the article is not talking about "more condescending" language but specifically about language that's less formal and at a lower grade level. I'm not sure if condescending answers are automatically also "dumbed down". I also think the way training text is gathered and fed into LLMs would separate different authors and context or we would see similar issues with all types of prompts. I can't definitely say it's not the reason but I think “language commonly used by women is more common in less formal texts” is a simpler and more convincing answer.