Refuse is different from verify you want to continue. "This looks like a bad idea because of (...). Are you sure you want to try this path anyway?" is not a refusal. And it covers both use cases.

The issue I ran into was that the LLMs won't recognize the bad ideas and just help you dig your hole deeper and deeper. Alternatively they will start circling back to wrong answers when suggestions aren't working or language features have been hallucinated, they don't stop an go: Hey, maybe what you're doing is wrong.

Ideally sure, the LLM could point out that your line of questioning is a result of bad design, but has anyone ever experienced that?