Then it's stupid and you're going to have an inevitable failure. Hopefully without any expensive sounds, so don't put LLMs in charge of heavy machinery or medical devices.
What we're discussing is whether a set of heuristics to determine whether something is the output of a human or an LLM are "stupid", not whether we should put LLMs in charge of critical work. It's not the LLMs we're talking about, but the heuristics to detect them.
The person you initially replied to claimed the heuristics (to detect LLMs) are not stupid if they are shown to work (by detecting LLMs). The person they were replying to claimed such heuristics were useless.
I think the heuristics are stupid, but happen to work with the current round of LLMs. The next round of training will work to stop the heuristics working, since if they work it means the LLM isn't correctly guessing the next token a human would produce. I don't think LLMs will become indistinguishable from humans any time soon, but I think it'll be a very long back & forth of training & finding new heuristics.