I tend to think there's no such thing as a dumb question, or at least there shouldn't be.
Whether or not it's wise for someone with little navigational experience to be up there, the fact is that they
are there, so when speaking to people on the hill it's probably best to stick to information that's helpful to them. Judgement or "stronger" words of advice can wait until they're safely back on the ground, if necessary at all.
If you criticise anyone on the hill then they'll close up and probably not ask for help if they need it. Pride and fear of looking stupid is a very real thing*. I tend to find the best way to help people is just to open up and offer information, show them maps (photos of maps are helpful sometimes) and answer questions. Usually they'll figure out that they're out of their depth themselves.
A couple of times I've offered to bring lost walkers down with me, which offers some time to gently suggest that trainers, jeans and no waterproofs or maps maybe wasn't the best idea for Scotland in autumn
*Amusingly in aviation, pilots that are unsure of their location are encouraged to request a "training fix" from the RAF Distress and Diversion Cell to establish their position. It's a judgement free way to double check your location without having to admit that you're lost or escalating the situation. It stops pride (something pilots suffer from rather a lot of) from becoming a killer....