But it's the human review that makes it not rude; not bothering to review means you're wasting the other person's time. If they wanted a chatbot response they could have went to the LLM directly.
It's like pointing to a lmgtfy link. That's _intentionally_ rude, in that it's normally used when the question isn't worth the thought. That's what pasting a chatbot response says.
I don't see any problem sharing a human-reviewed LLM output.
(I also figure that human review may not be that necessary in a few years.)