Multiple times recently, I have seen questions on Worldbuilding which I have been concerned about. Many of them could easily be masked attempts at asking for advice for criminal activity. One such recent question was about how to get yourself alone with the president; that one I can see being legite but it still caused me to raise an eyebrow.
The most recent example of this is the most blatant so far: How can I build a nuclear reactor in my backyard?
I can completely understand having a story where your average Joe has their own nuclear reactor. That is fine. Having a story with nuclear reactors does not require a question like this.
There are a lot of very smart people on here answering questions. I fear that if you are not careful, worldbuilding could be a place where people secretly scheme some bad stuff with unknowing helpers.
Should questions that could be used for nefarious purposes be off-topic? I'm not saying they definitely should be, but I am leaning toward yes. If you go to a chemistry stack exchange and ask "What chemicals do I need to make the cheapest IED?" as opposed to asking about some specific chemicals and their properties; you'll likely get deleted and reported to authorities. I suppose the metric should be something like "Are these questions more like asking for an IED or more like asking an innocent question about chemicals which just coincidentally happen to be used in explosives among other things?"
Other posts which I thought odd were ones about breaking and entering, stealing, assassinating, etc. in various fantasy settings, for which answers were often like "Your setting doesn't really change the basic facts, so you would do it just like you would in real life, and here is the best way to do it for real..." But this one about nuclear reactors seems even less reasonable than those.