Why not? You seem to underestimate the ability of AI tools to understand code. Undefined behavior is something that a good AI tool may avoid without major problems.
The issue to me is not the generation of code. It's that the person using it is inexperienced with the given language. We will never be able to place 100% faith in AI. At least in my lifetime. Given that, I think it's a relative danger that is washed away in all the hype. A junior dev copy-pasting code from chatgpt. I couldn't imagine a more dangerous combination.
Junior dev copy-pasting from stack overflow: this is already happening! Whatever bad thing AI tools can do, this is already reality all over the world.
That's not even close to the same thing. Stack overflow posters don't hallucinate solutions, and in all but the most obscure questions, the selected answer will have been reviewed dozens of times over.
With ChatGPT you get exactly what it gives you which must be trusted as a source of truth. That's bad.